Unmanned ship virtual anchoring method based on water jet propulsion and unmanned ship

Abstract

The invention discloses an unmanned ship virtual anchoring method based on water jet propulsion and an unmanned ship, and the method comprises the steps: obtaining virtual anchoring task information and navigation information of the unmanned ship, the virtual anchoring task information comprises an anchor point position and an anchor chain length, and the navigation information of the unmanned ship comprises a current position and a current heading of the unmanned ship; the direction from the current position of the unmanned ship to the anchor point position is calculated to serve as the expected heading, a rudder angle control value is calculated through a heading keeping control method, and the heading of the unmanned ship is made to face the anchoring point all the time; the distance between the current position and the anchor point position is calculated, if the distance is smaller than the length of an anchor chain, the tipping bucket is set to be a median value, and if the distance is larger than the length of the anchor chain, a tipping bucket control value is calculated through a position control proportional differential controller to keep the position of the unmanned ship; and the rudder angle control value and the tipping bucket control value are issued to an execution mechanism of the water-jet propeller, and virtual anchoring of the unmanned ship is achieved. According to the invention, the unmanned ship resists external interference by self power and is kept near the virtual anchor point.

Description

Technical Field

[0001] This invention belongs to the field of autonomous navigation control technology for unmanned surface vessels, specifically relating to a virtual anchoring method for unmanned surface vessels based on water jet propulsion and the unmanned surface vessel itself. Background Technology

[0002] With the development of technologies such as perception, navigation, and control, the decision-making, planning, situational awareness, and navigation control capabilities of unmanned surface vessels (USVs) have gradually improved. Currently, in some mission scenarios, USVs are gradually replacing manned vessels. When USVs perform missions, they are often required to temporarily stand by near designated locations or remain stationary for extended periods for reconnaissance. For small and medium-sized USVs, anchor chains are generally not equipped, and even if they are, the time required to deploy and retrieve them is relatively long, which cannot meet the requirement for USVs to be ready to deploy from standby status at any time. In addition, some USVs are equipped with dynamic positioning capabilities. Compared to dynamic positioning, virtual anchoring significantly reduces the frequency and amplitude of attitude and position adjustments, reducing energy consumption during on-duty operations and mechanical wear caused by frequent power system movements, thus offering economic advantages. For these scenarios of fixed-point on-duty or temporary standby, USVs need to use their own power to resist the effects of wind, waves, and currents, remaining near a designated location like an anchor being dropped in place. Therefore, researching a method for virtual anchoring of USVs has significant practical implications. Summary of the Invention

[0003] The purpose of this invention is to provide a virtual anchoring method for unmanned surface vessels (USVs) based on water jet propulsion, and the USV itself, which enables USVs to resist the effects of wind, waves, and currents and remain near a designated location without relying on anchor chains, using only their own power, thus meeting the mission requirements of USVs such as on-site standby and fixed-point duty.

[0004] The technical solution adopted in this invention is as follows: The first aspect of the present invention provides a virtual anchoring method for unmanned surface vessels based on waterjet propulsion, characterized in that the method includes: Acquire virtual anchoring mission information and unmanned surface vessel (USV) navigation information, whereby the virtual anchoring mission information includes anchor point location. and anchor chain length The navigation information of the unmanned surface vessel includes its current location. and current heading ; Calculate the current position of the unmanned surface vessel. to anchor point The direction is taken as the desired heading. The rudder angle control value was calculated using the heading hold control method. This ensures that the bow of the unmanned surface vessel always faces the anchorage point; Calculate the current position of the unmanned surface vessel. to anchor point distance If it is less than the length of the anchor chain Then set the tipping bucket to the median value. If it is greater than the length of the anchor chain The tipping control value is then calculated using a position control proportional-derivative controller. To maintain the position of the unmanned surface vessel; rudder angle control value and tipping control value The actuators are sent to the waterjet propulsion system to drive the unmanned surface vessel (USV) to make corresponding adjustments to its heading and position, thus enabling the USV to virtually anchor.

[0005] In the above scheme, the bow-holding control method includes: According to the desired heading Current heading of the unmanned surface vessel Calculate heading error ; Based on heading error Its differential components are used to calculate the rudder angle control value through a bow control proportional-derivative controller. .

[0006] In the above scheme, the specific bow-holding control method is as follows: Calculate heading error ; The rudder angle control value is calculated using a proportional-derivative controller for bow control. :

[0007] In the formula, This is the proportional adjustment coefficient. This is the differential adjustment coefficient.

[0008] In the above scheme, the maximum rudder angle is set. and minimum rudder angle If the rudder angle control value Greater than the maximum rudder angle Then the rudder angle control value Take the maximum rudder angle If the rudder angle control value Less than the minimum rudder angle Then the rudder angle control value Take the minimum rudder angle .

[0009] In the above scheme, the main unit is idling, the nozzle direction is in the center position, and the tipping bucket is in the center position value. At that time, the unmanned surface vessel remained stationary and did not move.

[0010] In the above scheme, the median value The testing method is as follows: Place the unmanned surface vessel (USV) in still water, set the main engine to idle speed, and adjust the nozzle direction to the center position. Continuously adjust the tipping value to observe the USV's speed and position until the USV comes to a complete stop in the water. Record the tipping value at this point as the center value. .

[0011] In the above scheme, the current position of the unmanned surface vessel is calculated. to anchor point distance If it is less than the length of the anchor chain Then set the tipping bucket to the median value. If it is greater than the length of the anchor chain The tipping control value is then calculated using a position control proportional-derivative controller. To maintain the position of the unmanned surface vessel, including: Calculate the current position of the unmanned surface vessel. to anchor point distance ; According to distance With anchor chain length Calculate anchoring error :

[0012] definition At this time, the tipping bucket is fully raised, that is... The smaller the angle, the higher the tipping bucket can be raised, and the greater the forward force generated. when hour, ; when At that time, the tipping control value is calculated by the position control proportional-derivative controller. :

[0013] in, This is the proportional adjustment coefficient. This is the differential adjustment coefficient.

[0014] In the above scheme, when At that time, the current position of the unmanned surface vessel to anchor point distance The farther away, The smaller.

[0015] In the above scheme, the anchor chain length It is 15 meters.

[0016] The second aspect of the present invention provides an unmanned surface vessel (USV) that employs the waterjet propulsion-based virtual anchoring method for USVs as described in any one of the first aspects.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects: This invention is compatible with most waterjet-driven unmanned surface vessels (USVs) and can be deployed in the algorithm library of USV controllers. It accepts calls from the USV controller and, through a waterjet-driven bow-holding control method and a virtual anchoring control method, enables the USV to maintain its position near a virtual anchor point using its own power to resist external interference. Furthermore, when controlling the USV's position, this invention typically uses a tipping bucket to generate thrust, avoiding frequent control of the main engine throttle, reducing main engine wear and fuel consumption, and achieving the need for fixed-point monitoring in a more energy-efficient and environmentally friendly manner. Attached Figure Description

[0018] Figure 1 A schematic diagram illustrating the impact of external interference on an unmanned surface vessel under bow control, provided as an embodiment of the present invention; Figure 2 This is a schematic diagram illustrating the definition of position control parameters provided in an embodiment of the present invention; Figure 3 A flowchart of a virtual anchoring control method provided in an embodiment of the present invention; Figure 4 A virtual anchoring position trajectory diagram of an unmanned surface vessel provided in an embodiment of the present invention; Figure 5 This is a schematic diagram showing the distance between the location of an unmanned surface vessel and its anchorage point, provided as an embodiment of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments provided by this invention without inventive effort are within the scope of protection of this invention.

[0020] Obviously, the accompanying drawings described below are merely some examples or embodiments of the present invention. Those skilled in the art can apply the present invention to other similar scenarios based on these drawings without any inventive effort. Furthermore, it is understood that although the efforts made in this development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this invention, modifications to design, manufacturing, or production based on the technical content disclosed in this invention are merely conventional technical means and should not be construed as insufficient disclosure of the present invention.

[0021] In this invention, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention may be combined with other embodiments without conflict.

[0022] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "a," "an," "an," "the," and similar words used in this invention do not indicate quantity limitation and may indicate singular or plural. The terms "comprising," "including," "having," and any variations thereof used in this invention are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units not listed, or may include other steps or units inherent to these processes, methods, products, or devices. The terms "connected," "linked," "coupled," and similar words used in this invention are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "A plurality" in this invention refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships may exist; for example, "A and / or B" can represent: A alone, A and B simultaneously, and B alone. The character " / " generally indicates that the preceding and following objects have an "or" relationship. The terms "first," "second," and "third" used in this invention are merely to distinguish similar objects and do not represent a specific ordering of the objects.

[0023] The purpose of this invention is to provide a virtual anchoring method and an unmanned surface vessel (USV) based on waterjet propulsion. This method enables the USV to resist the effects of wind, waves, and currents and remain stationary near a designated location using only its own power without relying on anchor chains, thus meeting the mission requirements of USVs for on-site standby and fixed-point monitoring. Specifically, to address the issue of the bow always needing to face the anchor point during virtual anchoring, a bow-keeping control method based on waterjet propulsion is proposed, solving the problem of the USV struggling to maintain a designated bow direction. For the control process of fixed-point monitoring of the USV, a virtual anchoring control method is proposed, which can achieve the effect of anchoring and remaining near a designated location based on the platform's navigation attitude information and anchoring mission parameters.

[0024] This invention provides a virtual anchoring method for unmanned surface vessels based on waterjet propulsion, such as... Figure 3 As shown, it includes: (1) Bow holding control method based on waterjet propulsion Unmanned surface vessels (USVs) powered by waterjet propulsion possess good maneuverability and can have their propulsion power controlled with high precision by adjusting the nozzle direction and the tipping bucket angle. Specifically, these USVs are equipped with waterjet propulsion and a tipping bucket. When the tipping bucket is raised, the waterjet propulsion sprays water backward, causing the USV to move forward. When the tipping bucket is lowered to the reversing position, the water jets sprayed by the waterjet propulsion reverse as they pass through the tipping bucket, meaning the waterjet propulsion sprays water forward through the tipping bucket, causing the USV to move backward.

[0025] When the tipping midpoint is unknown, it is necessary to obtain the tipping midpoint value of the unmanned surface vessel in still water. That is, in a still water environment, with the main unit idling, the nozzle direction in the center position, and the tipping bucket in the center position. During testing, the unmanned surface vessel (USV) can remain stationary. The specific testing method is as follows: Place the USV in still water, adjust the main engine to idle speed, and adjust the nozzle direction to near the center position. Observe the USV's speed and position by continuously adjusting the tipping value until the USV is almost stationary in the water, and record the tipping value at this point. .

[0026] When the main engine is idling and the bucket is in the neutral position, the unmanned surface vessel's rudder efficiency is poor, and the control exhibits significant hysteresis. Therefore, a proportional-derivative (PDT) controller is used to address the heading maintenance problem. As shown in Table 1, based on the error between the desired and current heading, and the differential component of this error, the control value (rudder angle) for the nozzle direction is calculated and output to the power system. The calculation method for the rudder angle control value is as follows:

[0027]

[0028] in, For heading error, For the desired heading, For the current heading, To control the rudder angle, This is the proportional adjustment coefficient. This is the differential adjustment coefficient.

[0029] Table 1. Pseudocode table of the heading hold control method based on waterjet propulsion.

[0030] Using the above rudder angle control methods It can maintain the unmanned surface vessel's bow orientation at a specified desired value.

[0031] (2) Virtual anchoring control method The virtual mooring control method is mainly divided into two parts: heading control and mooring point distance control.

[0032] ① Bow control Bow control is used to keep the bow of the unmanned surface vessel (USV) always facing the anchorage point. When the USV is not powered, it is affected by external factors such as wind, waves, and currents, causing it to move in a certain direction. By using bow control method 1, the USV's bow is kept always facing the anchorage point. Under the influence of external factors, the USV will remain stable on a straight line along the direction of external disturbances and passing through the virtual anchorage point, such as... Figure 1 As shown.

[0033] ② Position control After completing heading control, the unmanned surface vessel (USV) will remain on a straight line along the direction of external interference and past the virtual anchor point. At this point, the direction of the external force acting on the USV is generally backward. Therefore, the USV can maintain its position by generating a forward force to counteract the external influence. Generally, the external force acting on the USV is very small compared to its own power generation. Therefore, this method considers allowing the main engine to idle and controlling the magnitude of the forward propulsion force by controlling the lifting angle of the tipping bucket.

[0034] The position control strategy is similar to the idea of ​​a "spring anchor chain". When the unmanned surface vessel is within the length of the anchor chain, it does not perform position control actions. When the position of the unmanned surface vessel exceeds the length of the anchor chain, the farther away from the virtual anchor point, the greater the tension of the virtual anchor chain, which requires a greater forward thrust. This is reflected in the actuator as the higher the tipping bucket is raised.

[0035] like Figure 2 As shown, the calculation method for the tilting bucket lifting angle is as follows: Define the input "anchor chain length" parameter as follows The distance between the current position of the unmanned surface vessel and the virtual anchor point is The anchoring error is The calculation method is as follows:

[0036] The tipping control value is Defined here At this time, the tipping bucket is fully raised, that is... The smaller the angle, the higher the tipping bucket can be raised, and the greater the forward force generated. In the tipping position, no force is generated in the forward or backward direction. When hour .when At that time, the farther away from the virtual anchor point, The smaller the value, and considering the significant hysteresis in unmanned surface vessel control, a proportional-derivative controller is considered. The specific calculation method is as follows:

[0037] in, This is the proportional adjustment coefficient. This is the differential adjustment coefficient.

[0038] ③ Virtual anchoring control method Upon receiving the virtual anchoring task, the direction from the vessel to the virtual anchoring point is calculated in real time. This direction is used as the desired heading, and the heading control method is invoked to calculate the rudder angle control parameters. Simultaneously, the distance between the vessel and the virtual anchoring point is calculated in real time, and the control parameters for the tipping bucket are calculated using the position control method. The pseudocode for the virtual anchoring control method is shown in Table 2.

[0039] Table 2. Pseudocode Table of Virtual Anchoring Control Method

[0040] The flowchart of the virtual anchoring control method is as follows: Figure 3 As shown.

[0041] In addition, the present invention also provides an unmanned surface vessel that employs the water jet propulsion-based virtual anchoring method for unmanned surface vessels described in the above embodiments.

[0042] like Figure 3 As shown, the implementation method is as follows: 1. Virtual anchoring mission reception and submarine information collection Collect virtual anchoring mission information and the vessel's navigation information. The virtual anchoring mission information includes the anchor point location and anchor chain length, while the navigation information includes the vessel's current position and heading information.

[0043] 2. Bow control Calculate the direction from the vessel's position to the anchor point as the desired heading, call the heading hold method, and calculate the rudder angle control value.

[0044] 3. Position control Calculate the distance from the vessel to the anchor point. If it is less than the length of the anchor chain, set the tipping bucket to the neutral position. If it is greater than the length of the anchor chain, calculate the tipping bucket control value according to the proportional-derivative controller.

[0045] 4. Issuance of instructions The calculated tipping control value and rudder angle control value are sent to the actuator of the waterjet propulsion system, which can drive the unmanned surface vessel to complete the corresponding heading and position adjustments, achieving the effect of virtual anchoring of the unmanned surface vessel.

[0046] This invention was applied to a certain type of unmanned surface vessel (USV) and deployed, debugged, and tested in a reservoir. The anchor chain length was set to 15 meters. The test results are as follows: Figure 4 As shown. Figure 4 This is a virtual anchorage location trajectory diagram for the unmanned surface vessel. The pentagrams represent positioning points, and the black lines represent the trajectory.

[0047] After the unmanned surface vessel applies this invention, it will be able to... Figure 5 It can be seen that, under the influence of external environmental disturbances such as wind, waves, and currents, the unmanned surface vessel gradually stabilized at a distance of about 15 meters from the anchor point, and gradually tended to stabilize within a range of about 5 meters. From Figure 4 As can be seen, the trajectory of the unmanned surface vessel deviated to the southwest due to the influence of the external environment. After adjustment by the present invention, it gradually stabilized at about 15 meters in the southwest direction. This actual test of the unmanned surface vessel verified the practicality and effectiveness of the present invention.

[0048] In summary, this invention is compatible with most waterjet-driven unmanned surface vessels (USVs) and can be deployed in the algorithm library of USV controllers. It accepts calls from the USV controller and, through a waterjet-driven bow-holding control method and a virtual anchoring control method, enables the USV to maintain its position near a virtual anchor point using its own power to resist external interference. Furthermore, when controlling the USV's position, this invention generally uses a tipping bucket to generate thrust, avoiding frequent control of the main engine throttle, reducing main engine wear and fuel consumption, and achieving the need for fixed-point monitoring in a more energy-efficient and environmentally friendly manner.

[0049] It should be noted that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. In addition, depending on the implementation needs, the various steps / components described in this invention can be broken down into more steps / components, or two or more steps / components or parts of steps / components can be combined into new steps / components to achieve the purpose of this invention.

[0050] It will be readily understood by those skilled in the art that the above-described embodiments merely illustrate 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 patent should be determined by the appended claims.

Claims

1. A virtual anchoring method for unmanned surface vessels based on waterjet propulsion, characterized in that, The method includes: Acquire virtual anchoring mission information and unmanned surface vessel (USV) navigation information, whereby the virtual anchoring mission information includes anchor point location. and anchor chain length The navigation information of the unmanned surface vessel includes its current location. and current heading ; Calculate the current position of the unmanned surface vessel. to anchor point The direction is taken as the desired heading. The rudder angle control value was calculated using the heading hold control method. This ensures that the bow of the unmanned surface vessel always faces the anchorage point; Calculate the current position of the unmanned surface vessel. to anchor point distance If it is less than the length of the anchor chain Then set the tipping bucket to the median value. If it is greater than the length of the anchor chain The tipping control value is then calculated using a position control proportional-derivative controller. To maintain the position of the unmanned surface vessel; rudder angle control value and tipping control value The actuators are sent to the waterjet propulsion system to drive the unmanned surface vessel (USV) to make corresponding adjustments to its heading and position, thus enabling the USV to virtually anchor.

2. The virtual anchoring method for unmanned surface vessels based on waterjet propulsion according to claim 1, characterized in that, Bow-holding control methods include: According to the desired heading Current heading of the unmanned surface vessel Calculate heading error ; Based on heading error Its differential components are used to calculate the rudder angle control value through a bow control proportional-derivative controller. .

3. The virtual anchoring method for unmanned surface vessels based on waterjet propulsion according to claim 2, characterized in that, The specific bow-holding control method is as follows: Calculate heading error ; The rudder angle control value is calculated using a proportional-derivative controller for bow control. : In the formula, This is the proportional adjustment coefficient. This is the differential adjustment coefficient.

4. The virtual anchoring method for unmanned surface vessels based on waterjet propulsion according to any one of claims 1 to 3, characterized in that, Set the maximum rudder angle. and minimum rudder angle If the rudder angle control value Greater than the maximum rudder angle Then the rudder angle control value Take the maximum rudder angle If the rudder angle control value Less than the minimum rudder angle Then the rudder angle control value Take the minimum rudder angle .

5. The virtual anchoring method for unmanned surface vessels based on waterjet propulsion according to claim 1, characterized in that, In a still water environment, with the main unit idling, the nozzle direction at the neutral position, and the tipping bucket at the neutral position. At that time, the unmanned surface vessel remained stationary and did not move.

6. The virtual anchoring method for unmanned surface vessels based on waterjet propulsion according to claim 1 or 5, characterized in that, Median The testing method is as follows: Place the unmanned surface vessel (USV) in still water, set the main engine to idle speed, and adjust the nozzle direction to the center position. Continuously adjust the tipping value to observe the USV's speed and position until the USV comes to a complete stop in the water. Record the tipping value at this point as the center value. .

7. The virtual anchoring method for unmanned surface vessels based on waterjet propulsion according to claim 1, characterized in that, Calculate the current position of the unmanned surface vessel. to anchor point distance If it is less than the length of the anchor chain Then set the tipping bucket to the median value. If it is greater than the length of the anchor chain The tipping control value is then calculated using a position control proportional-derivative controller. To maintain the position of the unmanned surface vessel, including: Calculate the current position of the unmanned surface vessel. to anchor point distance ; According to distance With anchor chain length Calculate anchoring error : definition At this time, the tipping bucket is fully raised, that is... The smaller the angle, the higher the tipping bucket can be raised, and the greater the forward force generated. when hour, ; when At that time, the tipping control value is calculated by the position control proportional-derivative controller. : in, This is the proportional adjustment coefficient. This is the differential adjustment coefficient.

8. The virtual anchoring method for unmanned surface vessels based on waterjet propulsion according to claim 7, characterized in that, when At that time, the current position of the unmanned surface vessel to anchor point distance The farther away, The smaller.

9. The virtual anchoring method for unmanned surface vessels based on waterjet propulsion according to claim 1, characterized in that, Anchor chain length It is 15 meters.

10. An unmanned surface vessel, characterized in that, The unmanned surface vessel employs the virtual anchoring method for unmanned surface vessels based on water jet propulsion as described in any one of claims 1 to 9.

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