A converging-diverging unmanned surface vehicle swarm design method

Abstract

The application discloses a kind of unmanned ship cluster design methods of convergence, comprising the following steps: step 1, with the purpose of reducing total resistance and improving seakeeping when unmanned ship cluster is navigated in formation combination mode, design ship type;Step 2, design the connecting device of unmanned ship cluster;Step 3, design parallel type modular ship micro-grid;Step 4, design multi-boat power system and dynamics model;Step 5, design the overall tracking control strategy of unmanned ship cluster.The application proposes new type splicing drag reduction ship type, hull power integrated connecting device and other key innovations, and demonstrates and verifies the functions such as autonomous splicing, water patrol, target trapping of unmanned ship cluster through ship model test.

Description

Technical Field

[0001] This invention belongs to the field of shipbuilding and marine engineering technology, and discloses a method for designing a swarm of unmanned surface vessels that can be swarmed and dispersed. Background Technology

[0002] In recent years, with the development of unmanned surface vessel (USV) swarm technology, the concept of unmanned maritime combat is gradually shifting from a few large manned ship formations to a distributed fleet composed of numerous small platforms. Highly flexible small and medium-sized USVs can perform various missions, including surveillance, logistics, electronic warfare, expeditionary operations, and firepower projection, playing a crucial role in distributed fleets. Coupled with advanced USV swarm control technology, small and medium-sized USV swarms can achieve spatial dispersion and concentrated effectiveness. USV swarms can complete tasks collaboratively, improving overall efficiency. Individual vessels can also cooperate and perform multiple tasks simultaneously. The current development trend of maritime warfare is gradually evolving towards unmanned and swarm-based operations.

[0003] Current research on unmanned surface vessels (USVs) mainly focuses on small and medium-sized vessels. These USVs are limited by their displacement, carrying capacity, and range; they are overly reliant on their mother ships and have weak autonomous mission capabilities. Furthermore, the displacement and hull shape of small and medium-sized USVs may affect their seakeeping, limiting their survivability and navigation performance during independent navigation and operations. At the same time, the spatial dispersion of a large number of USVs makes resupply missions more difficult and significantly reduces resupply efficiency.

[0004] In conclusion, the continuous development and maturation of unmanned surface vessel (USV) swarm technology will provide my country with more flexible and efficient combat capabilities for maritime operations. The relatively poor endurance, high energy consumption, and low autonomous mission execution capability of USVs themselves are key challenges in USV swarm design. Similarly, solutions to support USV formations in long-distance transport and expeditionary operations are crucial areas requiring innovation in USV swarm design. Therefore, improving the performance of USVs through design and further ensuring the mission capabilities of USV swarms have become key technologies in USV swarm design. Summary of the Invention

[0005] This invention discloses a method for designing a swarm of unmanned surface vessels (USVs) capable of aggregation and dispersal, the method comprising the following steps:

[0006] Step 1: Design the ship type to reduce total resistance and improve seakeeping when the unmanned vessel swarm sails in formation mode;

[0007] Step 2: Design the connection device for the unmanned vessel swarm;

[0008] Step 3: Design a parallel modular ship microgrid;

[0009] Step 4: Design the multi-boat propulsion system and dynamic model;

[0010] Step 5: Design the overall tracking control strategy for the unmanned vessel swarm.

[0011] Step 1 also includes the following steps:

[0012] Step 11: The ship design adopts a rigidly connected following formation.

[0013] Step 12: Optimize using the principle of improving wave resistance through overall connection;

[0014] Step 13: Optimize by adopting the principle of reducing resistance through overall connection.

[0015] Furthermore, in step 11, the rigidly connected following formation of ships uses a bow-to-stern interlocking method during navigation, so that when connected, the bow of the aft ship can be inserted into the stern of the foreship. The grooves in the stern of the hull form a double stern, and the double stern causes the hull mass to be away from the centerline.

[0016] Specifically, the stern of the hull is equipped with a groove that matches the shape of the bow, in order to simultaneously reduce the frictional and compressive drag generated in this area, achieving the goal that the total resistance of the formation is less than the sum of the total resistance of each ship sailing separately:

[0017]

[0018] R t编队 For the total resistance of formation sailing, R ti Let n be the resistance of the i-th hull in the formation, and n be the total number of hulls in the formation.

[0019] Furthermore, in step 12, the overall connection provides advantages in wave resistance;

[0020] When the ship begins to list, its restoring moment is:

[0021]

[0022] In the formula, M R To restore torque, For high initial stability, it is related to the ship type, where φ is the heel angle and Δ is the displacement mass of the hull;

[0023] After being assembled as a whole, since the cross-section of the main body of the hull is the same as that of a single boat, the overall assembly... The displacement mass Δ of the hull remains unchanged. However, since the displacement mass Δ of the hull increases significantly after the overall splicing, the restoring moment M after splicing will remain unchanged at the same heel angle φ. R Larger than a single boat, the assembled vessel can withstand greater wave interference and has better seakeeping.

[0024] Furthermore, in step 13, the resistance advantages after the overall connection include frictional resistance R. f Advantages;

[0025] When a ship moves, a boundary layer forms around the hull due to the viscosity of water. This causes the hull to experience viscous shear stress, which in turn generates friction on the hull surface. The resultant force in the direction of motion is the frictional resistance R of the hull. f :

[0026] R f =-∫τcos(τ,x)dS

[0027] Where x is the direction of the ship's motion, S is the surface area of ​​the underwater part of the ship, and the fluid shear stress τ is:

[0028]

[0029] μ is the dynamic viscosity coefficient of the fluid. For velocity gradient;

[0030] In the scenario of unmanned surface vessels (USVs) swarming together, the velocity gradient of the fluid boundary layer in the gap between the hulls of the two vessels at the connection point is affected by the wake flow of the hulls. The surface area S of the underwater portion of the hull at the connection point between the two ships is very small, resulting in very low fluid shear stress within the hull boundary layer. Therefore, the surface area S of the underwater portion of the hull at the connection point can be approximated as the surface area of ​​the multi-ship connection. 连接 Excluding the surface area S of the underwater portion of a single vessel, compared to the dispersed navigation of unmanned vessels, the surface area S of the underwater portion of a single vessel is reduced by (n-1)S. 连接 Hull frictional resistance R f for:

[0031]

[0032] C f Let v be the average frictional drag coefficient, v be the speed of the unmanned surface vessel, and S be the surface area of ​​the underwater portion of the vessel. 连接 This refers to the surface area of ​​the underwater portion after multiple ships are connected.

[0033] Furthermore, in step 2, the connecting device includes a hull connecting device and an electrical connecting device;

[0034] The hull connection device is an electromagnetic adsorption device.

[0035] The power connection device is a contact metal plate installed at the stern and bow.

[0036] Furthermore, in step 3, the ship microgrid includes a power system, a control system, a sensing system, a propulsion system, a front connection device, and a rear connection device. The components are connected in parallel and powered by the power system.

[0037] The power system includes a series power supply and a blocking diode. When multiple unmanned surface vessel (USV) units are connected, the power supply for multiple USVs will be entirely supplied by the one with the larger voltage due to the presence of the blocking diode, thus realizing the functions of redundant power supply and dispatch power distribution.

[0038] Furthermore, in step 4, each unmanned surface vessel (USV) unit is equipped with two azimuth thrusters in the mid-to-rear section of the hull, and the USV's MMG maneuvering equations are:

[0039]

[0040] In the formula: m is the mass of the unmanned surface vessel; m x and m y These represent the additional mass of the unmanned surface vessel in the x-axis and y-axis directions, respectively; I z and J z , respectively, represent the moment of inertia of the hull about the z-axis and the moment of inertia of the added mass; u and v represent the longitudinal velocity and lateral velocity of the ship, respectively; r is the angular velocity of the hull about the z-axis. The accelerations obtained by differentiating the longitudinal velocity, lateral velocity, and rotational angular velocity are respectively; X H Y H and N H These are the longitudinal force, lateral force, and bow moment acting on the hull, excluding the propellers; X P Y P and N P These are the thrust, lateral force, and bow roll moment exerted by the propellers on the hull, respectively.

[0041] The thrust generated by the thruster is:

[0042]

[0043] In the formula, T L For the thrust generated by the left thruster, T R α is the thrust generated by the right thruster, α is the rudder angle, and l is the longitudinal distance from the thruster to the center of gravity of the unmanned surface vessel.

[0044] Furthermore, in step 4, the overall MMG control equation after the multiple boats are connected is:

[0045]

[0046] Each thruster can generate thrust of different magnitude and direction; the overall control force is:

[0047]

[0048] T1 to T6 represent the thrust generated by the six thrusters, and α1 to α6 represent the rudder angles of the six servo motors. n ,y n () represents the position of the propeller relative to the ship's center of gravity.

[0049] Furthermore, in step 5, in the overall assembly of the three unmanned surface vessel (USV) units connected together, which has six azimuth thrusters, thrusters 1 and 2 serve as the thrusters for the first USV at the front, thrusters 3 and 4 serve as the thrusters for the second USV in the middle, and thrusters 5 and 6 serve as the thrusters for the third USV at the rear. During the overall tracking process, the rudder angles of thrusters 3 and 4 remain constant at 0, and the turning torque is achieved by controlling the rudder angles of the thrusters of USV units 1 and 3.

[0050] When the unmanned surface vessel (USV) is at low speed, the first and third USV units, once connected, have opposite directions of rotation to obtain a greater turning torque and avoid insufficient turning.

[0051] When the unmanned surface vessel (USV) is at high speed, the first and third USV units, once connected, have the same steering direction, thereby obtaining a smaller turning torque and avoiding over-turning.

[0052] Furthermore, in step 5, the rudder angle α1 of the first unmanned surface vessel (USV) unit and the rudder angle α3 of the third USV unit are set to be proportional:

[0053] α1=kα3

[0054] Where k is a proportionality coefficient, the value of which is determined according to the speed v of the unmanned surface vessel. The lower the speed, the larger the rudder angle of the No. 1 unmanned surface vessel in reverse rotation, and the higher the speed, the larger the rudder angle of the No. 1 unmanned surface vessel in forward rotation.

[0055] Set to when the overall speed reaches maximum v max α1 = α3, i.e., k = 1. When the overall speed reaches its maximum and approaches 0, α1 = -α3, i.e., k = -1. The value of k is set to change linearly with speed v.

[0056]

[0057] Based on this rudder angle control strategy, similar to single-boat heading control, a PID controller can be set up to control the heading maintenance during the overall tracking process.

[0058] The beneficial effects achieved by this invention are:

[0059] The connected assembly offers four main advantages. First, its larger displacement provides excellent seakeeping capabilities. Second, the reduced wetted surface area and altered length result in decreased frictional and wave-making resistance, enhancing its speed during medium-speed cruising. Third, the connection device integrates the power systems of each unmanned surface vessel (USV) unit, enabling balanced energy consumption through real-time monitoring and scheduling. Fourth, the connected assembly allows for the deactivation of some USV units' sensing devices, such as GPS, to reduce energy consumption, while retaining common sensing devices like cameras across multiple USV units for wider detection range during cruising.

[0060] Upon reaching the designated area or detecting the target, the entire unmanned surface vessel (USV) can quickly disintegrate into individual USV units thanks to the rapid response of the connecting device. These dispersed USV units offer two main advantages: First, compared to a large ship, each dispersed USV unit has smaller inertia and turning radius, resulting in superior maneuverability compared to the connected unit. Second, the dispersed USVs possess a numerical advantage; combined with a USV swarm control system, they can achieve a spatially dispersed yet highly effective combat effect, accomplishing tasks such as area search and target acquisition. Attached Figure Description

[0061] Figure 1 This is a schematic diagram of the unmanned surface vessel (USV) designed according to the present invention;

[0062] Figure 2 This is a schematic diagram of the hull connection device designed in this invention;

[0063] Figure 3 This is a schematic diagram of the hull connection device designed in this invention;

[0064] Figure 4 This is a schematic diagram of the power connection device designed in this invention;

[0065] Figure 5 This is a schematic diagram of the ship microgrid designed according to the present invention;

[0066] Figure 6 This is a schematic diagram of the azimuth thruster in the unmanned surface vessel designed in this invention;

[0067] Figure 7 This is a schematic diagram of the force analysis of the unmanned surface vessel (USV) design of this invention under the condition of multiple vessels connected together;

[0068] Figure 8 This is a schematic diagram of the six azimuth thrusters in the three-vessel connection of the unmanned surface vessel designed in this invention;

[0069] Figure 9 This is a schematic diagram of the unmanned surface vessel designed in this invention turning at low speed when three vessels are connected;

[0070] Figure 10 This is a schematic diagram of the unmanned surface vessel (USV) designed in this invention turning at high speed when three USVs are connected. Detailed Implementation

[0071] The present invention will be further described below with reference to specific embodiments, and the advantages and features of the present invention will become clearer as a result. However, these embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. Those skilled in the art should understand that modifications or substitutions can be made to the details and form of the technical solutions of the present invention without departing from the spirit and scope of the present invention, but all such modifications and substitutions fall within the protection scope of the present invention.

[0072] The purpose of this invention is to provide a design method for a swarm of unmanned surface vessels (USVs) that can be assembled and disassembled. Based on key innovations such as the proposed novel modular drag-reducing hull type and integrated hull-electric connection device, a novel modular hull type and marine connection device are designed to achieve rigid connection of multiple small USVs, thereby improving the overall performance and combat capability of the USV swarm.

[0073] Step 1: Design the ship type to reduce the total resistance when the unmanned ship swarm sails in formation mode;

[0074] Specifically, it includes the following steps:

[0075] Step 11: The ship design adopts a rigidly connected following formation.

[0076] In terms of ship design concept, in order to reduce the total resistance when the unmanned ship swarm sails in formation combination mode, the present invention adopts a rigidly connected following formation.

[0077] Under the premise of rigid connection and formation following, in order to make the formation sailing advantageous in terms of ship resistance, it is necessary to achieve the goal of making the total resistance of the formation sailing less than the sum of the total resistance of the individual ships sailing separately, while ensuring good resistance performance of each individual ship.

[0078]

[0079] R t编队 For the total resistance of formation sailing, R ti Let n be the resistance of the i-th hull in the formation, and n be the total number of hulls in the formation.

[0080] To achieve this goal, this invention determines that unmanned surface vessel (USV) swarms use a bow-to-stern interlocking method during navigation. A novel USV design is developed so that, during connection, the bow of the aft vessel can insert into the stern of the preceding vessel. Specifically, this design involves designing a series of identical vessels, with grooves of the same shape as the bow cut into the sterns. Figure 1 As shown, this design ensures a tight connection between the two ships, thereby reducing both frictional and compressive drag generated in that section. The combination of multiple ships results in a slender, elongated assembly that offers superior drag resistance.

[0081] Step 12: Optimize using the principle of improving wave resistance through overall connection;

[0082] One advantage is the improved seakeeping performance after the entire structure is joined together. In the field of shipbuilding and marine engineering, the indicator for judging the stability of a well-designed ship is the restoring moment after it heaves, which can be calculated using the following formula:

[0083]

[0084] In the formula, M R To restore torque, For high initial stability, it is related to the ship type, where φ is the heel angle and Δ is the displacement mass of the hull;

[0085] After being assembled as a whole, since the cross-section of the main body of the hull is the same as that of a single boat, the overall assembly... The displacement mass Δ of the hull remains unchanged. However, since the displacement mass Δ of the hull increases significantly after the overall splicing, the restoring moment M after splicing will remain unchanged at the same heel angle φ. R Larger than a single boat, the assembled vessel can withstand greater wave interference and has better seakeeping.

[0086] Step 13: Optimize using the principle of reducing resistance through overall connection;

[0087] Secondly, there is the advantage of resistance after the overall connection. Specifically, this can be divided into frictional resistance R. f Advantages and wave-making resistance R w Advantages. When the ship moves, due to the viscosity of water, a boundary layer forms around the hull, causing the hull to be subjected to viscous shear stress during movement. This results in friction on the hull surface, and the net force in the direction of motion is the frictional resistance R. f ,have:

[0088] R f =-∫τcos(τ,x)dS (5)

[0089] Among them, the liquid shear stress τ is:

[0090]

[0091] In the scenario of unmanned surface vessels (USVs) swarming together, the velocity gradient of the fluid boundary layer in the gap between the hulls of the two vessels at the connection point is affected by the wake flow of the hulls. The stress is very small, resulting in very low fluid shear stress within the hull boundary layer at the junction of the two ships. Therefore, the stress at the junction of the hull S can be approximated as very low. 连接 The wetted surface area S is not included. Because the wetted surface area S is reduced by (n-1)S compared to the dispersed navigation of unmanned vessels. 连接 Then by

[0092]

[0093] It can be seen that the combined navigation of unmanned surface vessels can effectively reduce the total drag R of the combined vessel. t .

[0094] Because unmanned vessels navigate at the interface between water and air, the presence of free surfaces causes waves to form on the hull during movement, altering the static pressure distribution across the surface. Wave crests at the bow increase pressure at the bow, while wave troughs at the stern decrease pressure at the stern, creating a pressure difference between the bow and stern. This change in pressure distribution caused by wave-making generates resistance known as wave-making drag (R). w .

[0095] In one embodiment, the hull of the model ship used for demonstrating and verifying the technology is manufactured using 3D printing technology, and three azimuth thrusters are installed at the bottom of the ship. Due to the size constraints of the 3D printer, the total length of the hull does not exceed 0.8m, and the main dimensions of the final designed demonstration model ship are shown in Table 1.

[0096] Table 1 Main Dimensions of the Hull Model

[0097]

[0098] For unmanned surface vessels (USVs) swarming and sailing together, since the middle vessel is located approximately parallel to the mid-body in the swarm, it can be assumed that only the lead and stern vessels in the swarm experience significant wave-making resistance. At high speeds, since wave-making resistance constitutes the majority of the USV's overall resistance, reducing wave-making resistance through swarming and sailing together can lower the total resistance.

[0099] Step 2: Design the connection device for the unmanned vessel swarm;

[0100] The following section considers the design of the connection device. The connection device is one of the important components of this invention. Its main function is to connect the unmanned surface vessels (USVs) into a whole through rigid connection, and at the same time connect the USV hull, connect the power systems of each USV unit to realize energy scheduling between USV units.

[0101] The connection device consists of two parts: the hull connection device and the power connection device.

[0102] like Figure 2-3 As shown, the function of the hull connection device is to tightly connect the hulls of the fore and aft unmanned surface vessels (USVs). This invention uses an electromagnetic adsorption device to connect the hulls. This device generates a magnetic force of 70 kg when connected to a 12V power supply. Its switch can be controlled by a relay, and it has a power of 10W. It features low power consumption, strong attraction, and easy control, ensuring strong adsorption while consuming only a small amount of energy, thus meeting the requirements for connecting the fore and aft USV hulls in this invention.

[0103] like Figure 4 As shown, the function of the power connection device is to connect the power systems of the unmanned surface vessel (USV) unit into a whole. This invention selects a metal plate contact current-carrying device to connect the power system. The metal plate of this device connects the lines at both ends upon contact, can carry a maximum voltage of 36V and a current of 5A, and is wear-resistant and corrosion-resistant, thus meeting the requirements of this invention.

[0104] The hull connection device and the power connection device work in a similar way, both connecting through contact. Based on their working characteristics, the two are integrated into one as a connection device for unmanned surface vessel clusters.

[0105] Step 3: Design a parallel modular ship microgrid;

[0106] like Figure 5 As shown, the electronic components of each unmanned surface vessel (USV) unit include a power system, a control system, a sensing system, a propulsion system, a front connection device, and a rear connection device. All components on the vessel are connected in parallel and are powered by the power supply. The power system includes power supplies connected in series and blocking diodes. The electrical grid structure on each USV is identical. When multiple USVs are connected together, their electrical grids are also interconnected through the power connection device.

[0107] Once multiple unmanned surface vessel (USV) units are assembled, their local power supply systems can be combined to form a microgrid for the assembly. Considering the risk of circulating current overheating due to multiple batteries with different voltages connected in parallel, this invention solves this problem through a hardware design using a blocking diode. Its working principle is shown in the following figure:

[0108] Assume E1 > E2. Since the diode operating on the power supply side has a larger current, it is a high-power diode. Assume its forward voltage drop is 1V. Assuming diode D1 is forward-biased, the voltage across resistor R is:

[0109] U=E1-1 (8)

[0110] The operating current at this time:

[0111]

[0112] The forward conduction condition for diode D2 is:

[0113]

[0114] This contradicts the assumption. Therefore, diode D2 cannot conduct, I2 = 0, and the circulating current is blocked.

[0115] When multiple unmanned surface vessel (USV) units are spliced ​​together, the relay switch is turned on. Due to the presence of the blocking diode, the power supply of multiple USVs will be completely supplied by the one with the larger voltage (i.e., the one with more remaining power), thus realizing the functions of redundant power supply and dispatch power distribution.

[0116] Step 4: Design the multi-boat propulsion system and dynamic model;

[0117] To improve the flexibility of unmanned surface vessel (USV) heading control while ensuring uniform stress distribution on the hull, each USV unit is equipped with two azimuth thrusters in the mid-to-rear section of the hull. Figure 6 As shown.

[0118] A full-radius thruster generates a longitudinal force to control the longitudinal motion of the unmanned surface vessel (USV) and a turning torque to control its bow motion. Since the USV has three degrees of freedom in the horizontal plane—longitudinal, lateral, and bow-turning—it is an underactuated system. To achieve precise control of the USV unit, it is necessary to establish an accurate single-vessel dynamics model and design a reasonable USV motion control system.

[0119] For conventional unmanned surface vessels (USVs), although their actual motion has six degrees of freedom, there is a lack of effective means to control roll, pitch, and heave, and motion control mainly focuses on the USV's heading and surface position. Therefore, when studying the surface motion control problem of USVs, the motion of three degrees of freedom, namely heave, roll, and pitch, is usually ignored, and only the sway, roll, and bow motion in the horizontal plane are considered. According to the MMG model principle, the USV is divided into two parts, the hull and the propeller, for force analysis, thereby obtaining the MMG control equation of the USV, as shown in equation (11).

[0120]

[0121] In the formula: m is the mass of the unmanned surface vessel; m x and m y These represent the additional mass of the unmanned surface vessel in the x-axis and y-axis directions, respectively; I z and J z , respectively, represent the moment of inertia of the hull about the z-axis and the moment of inertia of the added mass; u and v represent the longitudinal velocity and lateral velocity of the ship, respectively; r is the angular velocity of the hull about the z-axis. The accelerations obtained by differentiating the longitudinal velocity, lateral velocity, and rotational angular velocity are respectively; XH Y H and N H These are the longitudinal force, lateral force, and bow moment acting on the hull, excluding the propellers; X P Y P and N P These are the thrust, lateral force, and bow roll moment exerted by the propellers on the hull, respectively.

[0122] The mass coefficient of the unmanned surface vessel (USV) can be obtained using CAD modeling software, and the hydrodynamics of the USV can be obtained using CFD fluid simulation software or ship model experiments. The thrust generated by the propeller is shown in equation (12).

[0123]

[0124] In the formula, T L For the thrust generated by the left thruster, T R α is the thrust generated by the right thruster, α is the rudder angle, and l is the longitudinal distance from the thruster to the center of gravity of the unmanned surface vessel.

[0125] Unlike unmanned surface vessel (USV) units, the connected system can generate longitudinal forces to control the overall longitudinal motion, lateral forces to control the overall lateral motion, and a turning torque to control the overall bow motion by adjusting the direction and speed of its six thrusters. This constitutes an overdrive system. Therefore, there is a problem of optimal thrust distribution during overall navigation.

[0126] Similar to the dynamic model of a single boat, according to the MMG method, the whole after multiple boats are connected can also be divided into two parts, the hull and the propeller, for force analysis, thereby obtaining the overall MMG control equation, as shown in equation (13).

[0127]

[0128] The difference is that the three unmanned surface vessel units connected together have six thrusters, each of which can generate thrust of different magnitude and direction. The overall control force can be obtained by equation (14).

[0129]

[0130] In the formula, T1 to T6 represent the thrust generated by the six propellers, α1 to α6 represent the rudder angles of the six servo motors, and (x n ,y n ) represents the position of the propeller relative to the ship's center of gravity, such as Figure 7 As shown.

[0131] Step 5: Design the overall tracking control strategy for the unmanned vessel swarm;

[0132] The three unmanned surface vessel (USV) units, when connected together, form a system with six azimuth thrusters, such as... Figure 8As shown, this is an overdrive system, meaning that the same horizontal control force can be achieved through multiple thruster combinations. Therefore, the thruster control needs to be constrained based on the overall navigation characteristics after connection and the position of each thruster.

[0133] For ease of control, all thrusters can be configured to have the same rotational speed, with thrusters 1 and 2, 3 and 4, and 5 and 6 having the same turning angle. Since thrusters 3 and 4 are closer to the overall center of gravity, they cannot generate a larger turning torque compared to the other thrusters. Therefore, during overall tracking, the rudder angles of thrusters 3 and 4 remain constant at 0. The turning torque is achieved by controlling the rudder angles of the thrusters in UAV units 1 and 3. Thus, the original six rotational speeds and six rudder angles are constrained to one rotational speed and two rudder angles, greatly simplifying the overall control of the UAV.

[0134] During tracking, the bow direction of the unmanned surface vessel (USV) is achieved by controlling the rudder angle of the thrusters to generate a bow torque. For the three USVs connected as a whole, the bow torque is generated by the rudder angles of USV unit 1 and USV unit 3. The rudder angle control strategies for USVs at low and high speeds will now be discussed.

[0135] At low speeds, unmanned surface vessels (USVs) have low propeller speeds and low thrust, resulting in relatively small turning torque through rudder angle control. This can lead to insufficient turning. However, USVs often operate in narrow waters at low speeds, requiring a small turning radius and a high turning speed. Therefore, in low-speed conditions, the rudder motors of USV units 1 and 3 have opposite steering directions to achieve greater turning torque and prevent insufficient turning. Figure 9 As shown.

[0136] At high speeds, unmanned surface vessels (USVs) experience high thrust and high propeller speeds, resulting in significant turning torque through rudder angle control. This can lead to oversteer. However, USVs need to maintain a certain level of heading stability at high speeds, and heading control must avoid excessive overshoot. Therefore, in high-speed operation, the servo motors of USV units 1 and 3 should have the same steering direction to achieve a smaller turning torque and prevent oversteer. Figure 10 As shown.

[0137] Based on this, the rudder angle α1 of unmanned surface vessel unit 1 and the rudder angle α3 of unmanned surface vessel unit 3 can be set to be proportional, that is...

[0138] α1=kα3 (15) where the value of k is determined based on the speed v of the unmanned surface vessel (USV). The lower the speed, the larger the rudder angle of USV unit 1 in reverse rotation; the higher the speed, the larger the rudder angle of USV unit 1 in forward rotation. Therefore, it can be set to be the rudder angle when the whole reaches the maximum speed v. max α1 = α3, i.e., k = 1. When the overall speed reaches its maximum and approaches 0, α1 = -α3, i.e., k = -1. The value of k is set to change linearly with speed v, therefore...

[0139]

[0140] Based on this rudder angle control strategy, similar to single-boat heading control, a PID controller can be set up to control the heading maintenance during the overall tracking process.

[0141] Similar to single-boat tracking, overall speed also needs to be controlled. Overall speed is also controlled using an incremental PID control algorithm.

[0142] The above are merely specific steps of the present invention and do not constitute any limitation on the scope of protection of the present invention; all technical solutions formed by equivalent transformation or equivalent substitution fall within the scope of protection of the present invention; the parts of the present invention not described in detail are common knowledge to those skilled in the art.

Claims

1. A method for designing a swarm of unmanned surface vessels capable of aggregation and dispersal, characterized in that, The method for designing a swarm of unmanned surface vessels that can be clustered and dispersed includes the following steps: Step 1: Design the ship type to reduce total resistance and improve seakeeping when the unmanned vessel swarm sails in formation mode; Step 2: Design the connection device for the unmanned vessel swarm; Step 3: Design a parallel modular ship microgrid; Step 4: Design the multi-boat propulsion system and dynamic model; Step 5: Design the overall tracking control strategy for the unmanned vessel swarm; Step 1 also includes the following steps: Step 11: The ship design adopts a rigidly connected following formation. Step 12: Optimize using the principle of improving wave resistance through overall connection; Step 13: Optimize using the principle of reducing resistance through overall connection; In step 5, the entire assembly of the three unmanned surface vessel (USV) units, consisting of six azimuth thrusters, consists of thrusters 1 and 2 for the first USV at the front, thrusters 3 and 4 for the second USV in the middle, and thrusters 5 and 6 for the third USV at the rear. During the overall tracking process, the rudder angles of thrusters 3 and 4 remain constant at 0, and the yaw torque is achieved by controlling the rudder angles of the thrusters of the first and third USV units. When the unmanned surface vessel (USV) is at low speed, the first and third USV units, once connected, have opposite directions of rotation to obtain a greater turning torque and avoid insufficient turning. When the unmanned surface vessel (USV) is at high speed, the first and third USV units, once connected, have the same steering direction, thereby obtaining a smaller turning torque and avoiding over-turning.

2. The method for designing a swarm of unmanned surface vessels that can be clustered and dispersed according to claim 1, characterized in that, In step 11, the rigidly connected following formation of ships uses a bow-to-stern interlocking method during navigation, so that when connected, the bow of the aft ship can be inserted into the stern of the foreship. The grooves in the stern of the hull form a double stern, which makes the hull mass away from the centerline. The stern section of the hull has a groove that matches the shape of the bow, in order to simultaneously reduce the frictional and compressive drag generated in this section, achieving the goal that the total resistance of the formation is less than the sum of the total resistance of the individual ships sailing separately: R t编队 For the total resistance of formation sailing, R ti Let n be the resistance of the i-th hull in the formation, and n be the total number of hulls in the formation.

3. The method for designing a swarm of unmanned surface vessels that can be clustered and dispersed according to claim 1, characterized in that, In step 12, the overall connection has the advantage of wave resistance; When the ship begins to list, its restoring moment is: In the formula, M R To restore torque, For high initial stability, it is related to the ship type, where φ is the heel angle and Δ is the displacement mass of the hull; After being assembled as a whole, because the cross-section of the main body of the hull is the same as that of a single boat, the overall assembly... The displacement mass Δ of the hull remains unchanged. However, since the displacement mass Δ of the hull increases significantly after the overall splicing, the restoring moment M after splicing will remain unchanged at the same heel angle φ. R Larger than a single boat, the assembled vessel can withstand greater wave interference and has better seakeeping.

4. The method for designing a swarm of unmanned surface vessels that can be clustered and dispersed according to claim 1, characterized in that, In step 13, the resistance advantage after the overall connection includes frictional resistance R. f Advantages; When a ship moves, a boundary layer forms around the hull due to the viscosity of water. This causes the hull to experience viscous shear stress, which in turn generates friction on the hull surface. The resultant force in the direction of motion is the frictional resistance R of the hull. f : R f =-∫τcos(τ,x)dS Where x is the direction of the ship's motion, S is the surface area of ​​the underwater part of the ship, and the fluid shear stress τ is: μ is the dynamic viscosity coefficient of the fluid. For velocity gradient; In the scenario of unmanned surface vessels (USVs) swarming together, the velocity gradient of the fluid boundary layer in the gap between the hulls of the two vessels at the connection point is affected by the wake flow of the hulls. The surface area S of the underwater portion of the hull at the connection point between the two ships is very small, resulting in very low fluid shear stress within the hull boundary layer. Therefore, the surface area S of the underwater portion of the hull at the connection point can be approximated as the surface area of ​​the multi-ship connection. 连接 Excluding the surface area S of the underwater portion of a single vessel, compared to the dispersed navigation of unmanned vessels, the surface area S of the underwater portion of a single vessel is reduced by (n-1)S. 连接 Hull frictional resistance R f for: C f Let v be the average frictional drag coefficient, v be the speed of the unmanned surface vessel, and S be the surface area of ​​the underwater portion of the vessel. 连接 This refers to the surface area of ​​the underwater portion after multiple ships are connected.

5. The method for designing a swarm of unmanned surface vessels that can be clustered and dispersed according to claim 1, characterized in that, In step 2, the connecting device includes a hull connecting device and an electrical connecting device; The hull connection device is an electromagnetic adsorption device. The power connection device is a contact metal plate installed at the stern and bow.

6. The method for designing a swarm of unmanned surface vessels that can be clustered and dispersed according to claim 1, characterized in that, In step 3, the ship microgrid includes a power system, a control system, a sensing system, a propulsion system, a front connection device, and a rear connection device. The components are connected in parallel and powered by the power system. The power system includes a series power supply and a blocking diode. When multiple unmanned surface vessel (USV) units are connected, the power supply for the USVs will be entirely supplied by the one with the larger voltage due to the presence of the blocking diode, thus realizing the functions of redundant power supply and dispatch power distribution.

7. The method for designing a swarm of unmanned surface vessels that can be clustered and dispersed according to claim 1, characterized in that, In step 4, each unmanned surface vessel (USV) unit is equipped with two azimuth thrusters in the mid-to-rear section of the hull. The MMG control equations for the USV are as follows: In the formula: m is the mass of the unmanned surface vessel; m x and m y These represent the additional mass of the unmanned surface vessel in the x-axis and y-axis directions, respectively; I z and J z , respectively, represent the moment of inertia of the hull about the z-axis and the moment of inertia of the added mass; u and v represent the longitudinal velocity and lateral velocity of the ship, respectively; r is the angular velocity of the hull about the z-axis. The accelerations obtained by differentiating the longitudinal velocity, lateral velocity, and rotational angular velocity are respectively; X H Y H and N H These are the longitudinal force, lateral force, and bow moment acting on the hull, excluding the propellers; X P Y P and N P These are the thrust, lateral force, and bow roll moment exerted by the propellers on the hull, respectively. The thrust generated by the thruster is: In the formula, T L For the thrust generated by the left thruster, T R α is the thrust generated by the right thruster, α is the rudder angle, and l is the longitudinal distance from the thruster to the center of gravity of the unmanned surface vessel.

8. The method for designing a swarm of unmanned surface vessels that can be clustered and dispersed according to claim 7, characterized in that, In step 4, the overall MMG maneuvering equations after the multiple boats are connected are: Each thruster can generate thrust of different magnitude and direction; the overall control force is: T1 to T6 represent the thrust generated by the six thrusters, and α1 to α6 represent the rudder angles of the six servo motors. n ,y n () represents the position of the propeller relative to the ship's center of gravity.

9. The method for designing a swarm of unmanned surface vessels that can be clustered and dispersed according to claim 1, characterized in that, In step 5, the rudder angle α1 of the first unmanned surface vessel (USV) unit and the rudder angle α3 of the third USV unit are set to be proportional: α1＝kα3 Where k is a proportionality coefficient, the value of which is determined according to the speed v of the unmanned surface vessel. The lower the speed, the larger the rudder angle of the No. 1 unmanned surface vessel in reverse rotation, and the higher the speed, the larger the rudder angle of the No. 1 unmanned surface vessel in forward rotation. Set to when the overall speed reaches maximum v max α1 = α3, i.e., k = 1. When the overall speed reaches its maximum and approaches 0, α1 = -α3, i.e., k = -1. The value of k is set to change linearly with speed v. Based on this rudder angle control strategy, similar to single-boat heading control, a PID controller can be set up to control the heading maintenance during the overall tracking process.

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