Collapsible unmanned ship cluster design method

Abstract

The invention discloses a method for designing a convergent and divergent unmanned ship cluster. The method comprises the following steps: step 1, designing a ship type for reducing total resistance and improving seakeeping when an unmanned ship cluster sails in a formation combination mode; 2, designing a connecting device of the unmanned ship cluster; 3, designing a parallel modular ship micro-grid; 4, designing a multi-boat power system and a dynamic model; and 5, designing an overall tracking control strategy of the unmanned ship cluster. The invention provides key innovations such as a novel splicing anti-drag ship type and a ship body electric power integrated connecting device, and the functions of autonomous splicing, water surface patrol, target surrounding and the like of an unmanned ship cluster are verified through ship model test demonstration.

Description

Technical Field

[0001] The invention belongs to the technical field of ship and ocean engineering, and discloses a design method for a cluster of unmanned boats that can gather and disperse. Background Art

[0002] In recent years, with the development of unmanned boat swarm technology, the concept of unmanned warfare at sea is gradually shifting from a few large manned ship formations to a distributed fleet composed of a large number of small platforms. Highly flexible small and medium-sized surface unmanned ships can perform a variety of missions such as surveillance, logistics, electronic warfare, expeditionary warfare and firepower delivery, and can play a key role in distributed fleets. With advanced unmanned boat swarm control technology, small and medium-sized surface unmanned boat swarms can achieve the purpose of spatial dispersion and efficiency concentration. Unmanned boat swarms can complete tasks through collaborative work and improve overall efficiency. Each boat can also divide the work and cooperate to perform multiple tasks at the same time. Today's development direction of maritime warfare is gradually evolving towards unmanned and clustered.

[0003] At present, the research on unmanned boats mainly focuses on small and medium-sized ones. Small and medium-sized unmanned boats are limited by displacement, limited carrying load, short endurance, over-reliance on mother ships, and weak ability to perform tasks autonomously. In addition, the displacement and boat type of small and medium-sized unmanned boats may affect their seakeeping, limiting their independent navigation, survivability and navigation performance during operation. At the same time, the spatial dispersion of a large number of unmanned boats also makes the supply mission more difficult, greatly reducing the efficiency of supply.

[0004] In summary, the continuous development and maturity of unmanned boat swarm technology will provide more flexible and efficient combat capabilities for my country's maritime operations. The poor endurance, high energy consumption and low autonomous mission execution capabilities of unmanned boats are key challenges in the design of unmanned boat swarms. The solution to support unmanned surface boat formations to perform long-distance transportation and expeditionary combat missions is also the key to innovation in the design of unmanned boat swarms. Therefore, how to improve the performance of unmanned boats through design and further ensure the mission capabilities of unmanned boat swarms has become a key technology in the design of unmanned boat swarms. Summary of the invention

[0005] The present invention discloses a method for designing a cluster of unmanned boats that can gather and disperse, and the method for designing a cluster of unmanned boats that can gather and disperse comprises the following steps:

[0006] Step 1: Design the ship type with the purpose of reducing the total resistance and improving the seakeeping performance when the unmanned ship cluster sails in a formation combination mode;

[0007] Step 2, design the connection device of the unmanned ship cluster;

[0008] Step 3, design a parallel modular ship microgrid;

[0009] Step 4, design the multi-boat power system and dynamics model;

[0010] Step 5: Design the overall tracking control strategy for the unmanned ship cluster.

[0011] In step 1, the following steps are also included:

[0012] Step 11, the ship design adopts a rigidly connected following formation;

[0013] Step 12, optimizing by adopting the principle of overall connection to improve seakeeping performance;

[0014] Step 13, optimize using the principle of overall connection to reduce resistance.

[0015] Furthermore, in step 11, the rigidly connected following formation ship type uses a method of embedding the bow and stern into each other when sailing, so that the bow of the rear ship can be inserted into the stern of the front ship when connected, and the grooves of the stern of the hull form a double stern, and the double stern makes the hull mass away from the center longitudinal line;

[0016] Specifically, the stern of the hull is provided with a groove matching the shape of the bow to simultaneously reduce the friction resistance and pressure resistance generated by this part, so as to achieve the goal that the total resistance of the formation sailing is less than the sum of the total resistance of each ship sailing separately:

[0017]

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

[0019] Furthermore, in step 12, the overall connection has the advantage of seakeeping;

[0020] When the hull heels, the restoring moment is:

[0021]

[0022] Where M R is the restoring torque, It is the initial stability, which is related to the ship type, φ is the heel angle, and Δ is the displacement mass of the hull;

[0023] After the whole is spliced, the cross section of the main part of the hull is the same as that of the single boat, so after the whole is spliced unchanged, since the displacement mass Δ of the hull increases exponentially after the whole splicing, the restoring moment M after splicing at the same heel angle φ R It is larger than a single boat and can resist greater wave interference after being spliced ​​as a whole, and has better seakeeping performance.

[0024] Furthermore, in step 13, the resistance advantage after the overall connection includes the friction resistance R f Advantages:

[0025] When the hull moves, due to the viscosity of water, a boundary layer is formed around the hull, so that the hull is subjected to viscous shear stress during movement, that is, friction is generated on the surface of the hull. Its combined force in the direction of movement is the friction 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, is the velocity gradient;

[0030] For the combined navigation condition of unmanned ship clusters, in the gap between the two ship hulls, the velocity gradient of the fluid boundary layer is affected by the wake of the hull. The shear stress of the fluid in the boundary layer of the hull at the connection between the two ships is very small, and it can be approximately considered that the surface area S of the underwater part of the multiple ships connected to the hull is 连接 The surface area S of the underwater part of a single ship is not taken into account. Compared with the dispersed navigation of unmanned ships, the surface area S of the underwater part of a single ship is reduced by (n-1)S. 连接 , hull friction resistance R f for:

[0031]

[0032] C f is the average friction resistance coefficient, v is the speed of the unmanned boat, S is the surface area of ​​the underwater part of the single boat, S 连接 It is the surface area of ​​the underwater part after multiple ships are connected.

[0033] Furthermore, in step 2, the connection device includes a hull connection device and an electric power connection device;

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

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

[0036] Furthermore, in step 3, the ship microgrid includes a power supply system, a control system, a sensing system, a power system, a front connection device and a rear connection device, and the connection between the components is in parallel, and the power supply system is used for power supply;

[0037] The power supply system includes a power supply and a circulating current blocking diode connected in series. When multiple unmanned boat units are connected, due to the presence of the circulating current blocking diode, the power supply of multiple unmanned boats will be completely supplied by the side with a larger voltage, realizing the functions of redundant power supply and dispatching power distribution.

[0038] Furthermore, in step 4, each unmanned boat unit carries two full-rotation thrusters in the middle and rear section of the hull, and the MMG maneuvering equation of the unmanned boat is:

[0039]

[0040] Where: m is the mass of the unmanned boat; m x and m y are the additional masses of the unmanned boat in the x-axis and y-axis directions respectively; I z and J z are the moment of inertia of the hull around the z-axis and the moment of inertia of the additional mass, respectively; u and v are the longitudinal velocity and transverse velocity of the ship, respectively; r is the angular velocity of the hull around the z-axis; are the accelerations derived from the longitudinal velocity, lateral velocity and angular velocity respectively; X H , Y H and N H are the longitudinal force, lateral force and bow moment of all external forces acting on the hull except the propeller; X P , Y P and N P are respectively the thrust, transverse force and bow pitch moment exerted by the propeller on the hull;

[0041] The thrust generated by the thruster is:

[0042]

[0043] Where, T L is the thrust generated by the left thruster, T R 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 boat.

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

[0045]

[0046] Each thruster can generate thrust of different magnitudes and directions, and the overall control force is:

[0047]

[0048] T1~T6 are the thrusts generated by the six thrusters, α1~α6 are the rudder angles of the six steering gears, (x n ,y n ) is the position of the propeller relative to the center of gravity of the hull.

[0049] Furthermore, in step 5, after the three unmanned boat units are connected, the whole has six full-rotation thrusters, thrusters No. 1 and No. 2 are thrusters for the first unmanned boat in the front, thrusters No. 3 and No. 4 are thrusters for the second unmanned boat in the middle, and thrusters No. 5 and No. 6 are thrusters for the third unmanned boat in the back; during the overall tracking process, the rudder angles of thrusters No. 3 and No. 4 remain unchanged at 0, and the bow torque is achieved by controlling the rudder angles of the thrusters of the No. 1 unmanned boat unit and the No. 3 unmanned boat unit;

[0050] When the unmanned boat is at a low speed, the first unmanned boat unit and the third unmanned boat unit have opposite directions after being connected, so as to obtain a larger bow turning moment and avoid the situation of insufficient bow turning;

[0051] When the unmanned boat is at high speed, the first unmanned boat unit and the third unmanned boat unit have the same steering direction after being connected at high speed, so as to obtain a smaller bow turning torque and avoid excessive bow turning.

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

[0053] α1=kα3

[0054] Among them, k is the proportional coefficient, and its value is determined according to the speed v of the unmanned boat. The smaller the speed, the larger the rudder angle of the reverse rotation of the No. 1 unmanned boat unit, and the larger the speed, the larger the rudder angle of the forward rotation of the No. 1 unmanned boat unit;

[0055] Set to when the overall maximum speed v max , α1=α3, that is, k=1. When the overall maximum speed approaches 0, α1=-α3, that is, k=-1. The k value is set to change linearly with the speed v:

[0056]

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

[0058] The beneficial effects achieved by the present invention are:

[0059] The connected whole has the following four advantages. First, the connected whole has good wave resistance due to its displacement advantage. Second, due to the reduction of wet surface area and the change of ship length, the friction resistance and wave-making resistance of the connected whole are also reduced, making it faster during medium-speed cruising. Third, the connecting device connects the power systems of each unmanned boat unit on the basis of connecting the hull, and realizes balanced energy consumption of each ship through real-time monitoring and scheduling of the electric energy of each ship. Fourth, the connected whole can disable some sensing equipment of some unmanned boat units, such as GPS, to reduce the consumption of electric energy, and can also retain the same sensing equipment of multiple unmanned boat units, such as cameras, to achieve a wider range of detection during cruising.

[0060] After reaching the designated range or finding the target to be captured, the entire unmanned boat can be quickly split into individual unmanned boat units with the rapid response of the connection device. The dispersed unmanned boat units have the following two advantages. First, the dispersed unmanned boat units have smaller inertia and turning radius than large ships, so the maneuverability of each unmanned boat unit is better than the connected whole. Second, the dispersed unmanned boats have the advantage of quantity. With the unmanned boat cluster control system, they can achieve a combat effect of spatial dispersion and concentrated efficiency, and complete tasks such as regional search and target capture. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 It is a schematic diagram of the unmanned boat designed by the present invention;

[0062] Figure 2 is a schematic diagram of the hull connection device designed by the present invention;

[0063] Figure 3 is a schematic diagram of the hull connection device designed by the present invention;

[0064] Figure 4 is a schematic diagram of the power connection device designed by the present invention;

[0065] Figure 5 It is a schematic diagram of the ship microgrid designed by the present invention;

[0066] Figure 6 It is a schematic diagram of the full-rotation pusher in the unmanned boat designed by the present invention;

[0067] Figure 7 It is a schematic diagram of the force analysis of the unmanned boat type designed by the present invention when multiple boats are connected;

[0068] Figure 8 It is a schematic diagram of six azimuth thrusters in a three-boat connection of the unmanned boat model designed by the present invention;

[0069] Fig. 9 It is a schematic diagram of the unmanned boat type designed by the present invention turning at a low speed when three boats are connected;

[0070] Fig.10 It is a schematic diagram of the unmanned boat type designed by the present invention turning at a high speed when three boats are connected. DETAILED DESCRIPTION

[0071] The present invention will be further described below in conjunction with specific embodiments, and the advantages and features of the present invention will become clearer as the description proceeds. However, these embodiments are exemplary only and do not constitute any limitation to the scope of the present invention. It should be understood by those skilled in the art that the details and forms of the technical solution of the present invention may be modified or replaced without departing from the spirit and scope of the present invention, but these modifications and replacements all fall within the scope of protection of the present invention.

[0072] The purpose of the present invention is to provide a design method for a cluster of unmanned boats that can gather and disperse. Based on the proposed key innovations such as the new type of connectable drag-reducing ship type and the hull power integrated connection device, a new type of connectable ship type and a ship connection device are designed to achieve the rigid connection of multiple small unmanned boats, so as to improve the overall performance and overall combat capability of the unmanned boat cluster.

[0073] Step 1, designing a ship type for the purpose of reducing the total resistance when the unmanned ship cluster sails in a formation combination mode;

[0074] Specifically, the following steps are included:

[0075] Step 11, the ship design adopts a rigidly connected following formation;

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

[0077] Under the premise of rigid connection and following the formation, in order to make the formation sailing have advantages in terms of ship resistance, it is necessary to ensure that the total resistance of the formation sailing is less than the sum of the total resistance of each ship sailing separately while ensuring the good resistance performance of a single ship.

[0078]

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

[0080] In order to achieve this goal, the present invention determines that the unmanned boat cluster uses the method of embedding each other head and tail when sailing, and designs a new type of unmanned boat so that the bow of the rear ship can be inserted into the stern of the front ship when connected. The specific design method is to design a series of ships with the same ship type, and cut a groove with the same shape as the bow at the stern, such as Figure 1 As shown, the two ships are closely connected when connected, so as to reduce the friction resistance and pressure resistance generated by the part at the same time. After the multiple ships are combined, they become a combination of slender ships, which has better resistance performance.

[0081] Step 12, optimizing by adopting the principle of overall connection to improve seakeeping performance;

[0082] One is the advantage of seakeeping after overall connection. In the field of shipbuilding and marine engineering, the indicator for judging the stability of a well-designed ship is the righting moment after the ship heels, which can be calculated by the following formula:

[0083]

[0084] Where M R is the restoring torque, It is the initial stability, which is related to the ship type, φ is the heel angle, and Δ is the displacement mass of the hull;

[0085] After the whole is spliced, the cross section of the main part of the hull is the same as that of the single boat, so after the whole is spliced unchanged, since the displacement mass Δ of the hull increases exponentially after the whole splicing, the restoring moment M after splicing at the same heel angle φ R It is larger than a single boat and can resist greater wave interference after being spliced ​​as a whole, and has better seakeeping performance.

[0086] Step 13, optimizing by adopting the principle of overall connection to reduce resistance;

[0087] The second is the resistance advantage after the overall connection. Specifically, it can be divided into friction resistance R f Advantages and wave resistance R w When the hull moves, due to the viscosity of water, a boundary layer is formed around the hull, so that the hull is subjected to viscous shear stress during movement, that is, friction is generated on the surface of the hull, and its combined force in the direction of movement is the friction resistance R of the hull. f ,have:

[0088] R f = -∫τcos(τ,x)dS (5)

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

[0090]

[0091] For the combined navigation condition of unmanned ship clusters, in the gap between the two ship hulls, the velocity gradient of the fluid boundary layer is affected by the wake of the hull. The fluid shear stress in the boundary layer of the hull at the connection between the two ships is very small, so it can be approximately considered that the hull of the connection part S 连接 The wet surface area S is not taken into account. Compared with the dispersed navigation of unmanned ships, the wet surface area S is reduced by (n-1)S 连接 , and then by

[0092]

[0093] It can be obtained that the combined navigation of unmanned ship clusters can effectively reduce the total resistance of the combination R t .

[0094] Since the unmanned ship sails at the interface of water and air, due to the existence of free surface, the hull will generate waves during the movement, changing the static pressure distribution on the hull surface. The wave crest at the bow increases the pressure at the bow, while the wave trough at the stern reduces the pressure at the stern, thus generating a hydrodynamic pressure difference between the bow and stern. The resistance generated by the change in pressure distribution caused by wave making is called wave making resistance R. w .

[0095] In one embodiment, the hull of the ship model used for demonstration and verification of the technology is manufactured by 3D printing technology, and three full-rotation thrusters are installed on 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 demonstration ship model finally designed are shown in Table 1.

[0096] Table 1 Main dimensions of the hull model

[0097]

[0098] For the unmanned ship cluster combined navigation conditions, since the middle ship in the combination is basically located in a position approximately parallel to the mid-body, it can be considered that only the bow ship and the stern ship in the combination are subject to greater wave-making resistance; in the case of high-speed navigation, since wave-making resistance accounts for the main part of the unmanned ship's resistance, reducing wave-making resistance by cluster combined navigation can reduce the total resistance.

[0099] Step 2, design the connection device of the unmanned ship cluster;

[0100] Next, the design of the connection device is considered. The connection device is one of the important components of the present invention, and its main function is to connect the unmanned boats into a whole through rigid connection, and at the same time as connecting the hull of the unmanned boat, connect the power systems of each unmanned boat unit to realize energy scheduling between the unmanned boat units.

[0101] The connection device includes two parts: a hull connection device and an electric 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 front and rear unmanned boats. The present invention selects an electromagnetic adsorption device to connect the hulls. The device can generate 70kg of magnetic force after connecting to a 12V power supply, and its switch can be controlled by a relay with a power of 10W. It has the characteristics of low power, strong suction, and easy control. While ensuring the adsorption force, it only consumes a small amount of energy, which can meet the needs of connecting the front and rear unmanned boat hulls in the present invention.

[0103] like Figure 4 As shown, the function of the power connection device connects the power system of the unmanned boat unit as a whole. The present invention selects a metal sheet contact overcurrent device to connect the power system. The metal sheet of the device can connect the lines at both ends after contact, and can carry a maximum voltage of 36V and a current of 5A. It is also wear-resistant and corrosion-resistant, which can meet the needs of the present invention.

[0104] The hull connection device and the power connection device work in a similar manner, both of which are connected through contact. According to their working characteristics, the two are integrated into one as a connection device for the unmanned boat cluster.

[0105] Step 3, design a parallel modular ship microgrid;

[0106] like Figure 5 As shown, the electronic components of each unmanned boat unit include a power supply system, a control system, a perception system, a power system, a front connection device, and a rear connection device. All components on the boat are connected in parallel and are powered by a power supply. The power supply system includes a series power supply and a blocking diode. The power grid structure on each unmanned boat is the same. When multiple unmanned boats are spliced, the power grid of the unmanned boat is also connected through the power connection device.

[0107] When multiple unmanned boat units are combined, their local power supply systems can be combined to form a microgrid of the combination. Considering that multiple batteries with different voltages connected in parallel will cause dangerous overheating of the circulating current, the present invention solves this problem through the hardware design of the circulating current blocking diode. Its working principle is shown in the figure below:

[0108] Assume E1>E2. Since the diode working on the power supply side has a large current, it is a high-power diode, and its forward voltage drop is 1V. Assume that diode D1 is forward-conducting, so the voltage on resistor R is:

[0109] U=E1-1 (8)

[0110] The working current at this time:

[0111]

[0112] Then the forward conduction condition of diode D2 is:

[0113]

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

[0115] When multiple unmanned boat units are spliced ​​together and the relay switch is turned on, due to the presence of the circulating current blocking diode, the power supply of multiple unmanned boats will be completely supplied by the side with larger voltage (that is, the side with more remaining power), realizing the functions of redundant power supply and dispatching power distribution.

[0116] Step 4, design the multi-boat power system and dynamics model;

[0117] In order to improve the flexibility of the unmanned boat's heading control and ensure that the hull is evenly stressed, each unmanned boat unit is equipped with two full-rotation thrusters in the middle and rear section of the hull, such as Figure 6 shown.

[0118] The full-rotation thruster can generate longitudinal force to control the longitudinal motion of the unmanned boat and bow torque to control the bow motion of the unmanned boat. The unmanned boat has three degrees of freedom in the horizontal plane: longitudinal, lateral, and bow, so the unmanned boat unit is an under-actuated system. To achieve precise control of the unmanned boat unit, it is necessary to establish a precise single boat dynamics model and design a reasonable unmanned boat motion control system.

[0119] For conventional surface unmanned boats, although their actual motion has six degrees of freedom, there is a lack of effective means to control roll, pitch and heave, and the motion control is mainly concerned with the heading and surface position of the unmanned boat. Therefore, when studying the surface motion control problem of unmanned boats, the motion of three degrees of freedom such as heave, roll and pitch is usually ignored, and only the sway, swing and bow motion in the horizontal plane are considered. According to the MMG model principle, the unmanned boat is divided into two parts: the hull and the propeller for force analysis, and the MMG control equation of the unmanned boat is obtained, as shown in formula (11).

[0120]

[0121] Where: m is the mass of the unmanned boat; m x and m y are the additional masses of the unmanned boat in the x-axis and y-axis directions respectively; I z and J z are the moment of inertia of the hull around the z-axis and the moment of inertia of the additional mass, respectively; u and v are the longitudinal velocity and transverse velocity of the ship, respectively; r is the angular velocity of the hull around the z-axis; are the accelerations derived from the longitudinal velocity, lateral velocity and angular velocity respectively; XH , Y H and N H are the longitudinal force, lateral force and bow moment of all external forces acting on the hull except the propeller; X P , Y P and N P They are respectively the thrust, lateral force and bow pitch moment exerted by the propeller on the hull.

[0122] The mass coefficient of the unmanned boat can be obtained through CAD modeling software, and the hydrodynamic force of the unmanned boat can be obtained through CFD fluid simulation software or ship model test. The thrust generated by the propeller is shown in formula (12).

[0123]

[0124] Where, T L is the thrust generated by the left thruster, T R 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 boat.

[0125] Unlike the unmanned boat unit, the connected whole can generate longitudinal force to control the overall longitudinal movement, lateral force to control the overall lateral movement, and bow turning torque to control the overall bow turning movement by adjusting the direction and speed of the six thrusters. It is an overdrive system. There is a problem of optimizing thrust distribution during overall navigation.

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

[0127]

[0128] The difference is that after the three unmanned boat units are connected, the whole has six thrusters, each of which can generate thrust of different sizes and directions. The overall control force can be obtained by formula (14).

[0129]

[0130] Where, T1~T6 are the thrusts generated by the six thrusters, α1~α6 are the rudder angles of the six steering gears, (x n ,y n ) is the position of the propeller relative to the center of gravity of the ship, such as Figure 7 shown.

[0131] Step 5: Design the overall tracking control strategy of the unmanned ship cluster;

[0132] The whole after the three unmanned boat units are connected has six full-rotation thrusters, such as Figure 8As shown, it belongs to an overdrive system, that is, the same horizontal plane control force has multiple thrust combinations. Therefore, it is necessary to constrain the control of the thrusters according to the characteristics of the overall navigation after connection and the position of each thruster.

[0133] For the convenience of control, all thrusters can be set to have the same speed, and thrusters No. 1 and No. 2, thrusters No. 3 and No. 4, and thrusters No. 5 and No. 6 have the same turning angle. Since thrusters No. 3 and No. 4 are closer to the overall center of gravity, they cannot generate a larger bow turning moment than other thrusters. Therefore, during the overall tracking process, the rudder angles of thrusters No. 3 and No. 4 remain unchanged at 0, and the bow turning moment is achieved by controlling the rudder angles of the thrusters of the No. 1 unmanned boat unit and the No. 3 unmanned boat unit. As a result, the original 6 speeds and 6 rudder angles are constrained to 1 speed and 2 rudder angles, greatly simplifying the overall control of the unmanned boat.

[0134] During the tracking process, the bow direction of the unmanned boat is achieved by controlling the rudder angle of the thruster to generate a bow torque. For the whole after the three boats are connected, the bow torque is generated by the rudder angles of the No. 1 unmanned boat unit and the No. 3 unmanned boat unit. The rudder angle control strategy of the unmanned boat at low speed and high speed is now discussed.

[0135] When the unmanned boat is at low speed, the propeller speed is low and the thrust is small. The bow turning torque formed by controlling the rudder angle is also small, which may cause insufficient bow turning. The sea conditions of the unmanned boat at low speed are often narrow waters, which require a smaller turning radius and a larger bow turning speed. Therefore, the steering gears of the No. 1 unmanned boat unit and the No. 3 unmanned boat unit have opposite directions at low speed after connection, so as to obtain a larger bow turning torque and avoid insufficient bow turning. Fig. 9 shown.

[0136] When the unmanned boat is at high speed, the propeller speed is high and the thrust is large. The bow turning torque formed by controlling the rudder angle is also relatively large, which may cause excessive bow turning. However, the unmanned boat needs to maintain a certain bow stability at high speed, and the bow control cannot have too much overshoot. Therefore, after the connection, the steering gears of the No. 1 unmanned boat unit and the No. 3 unmanned boat unit have the same steering direction at high speed to obtain a smaller bow turning torque and avoid excessive bow turning. Fig.10 shown.

[0137] On this basis, the rudder angle α1 of the No. 1 unmanned boat unit and the rudder angle α3 of the No. 3 unmanned boat unit can be set proportionally, that is,

[0138] α1=kα3 (15) The value of k is determined by the speed v of the unmanned boat. The smaller the speed, the greater the rudder angle of the No. 1 unmanned boat unit in reverse rotation, and the greater the speed, the greater the rudder angle of the No. 1 unmanned boat unit in forward rotation. Therefore, it can be set to when the overall maximum speed v is reached max , α1=α3, that is, k=1. When the overall maximum speed approaches 0, α1=-α3, that is, k=-1. The k value is set to change linearly with the speed v, so there is

[0139]

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

[0141] Similar to single boat tracking, the overall speed is also an object that needs to be controlled. The overall speed is also controlled based on the incremental PID control algorithm.

[0142] The above are only specific steps of the present invention and do not constitute any limitation to the protection scope of the present invention; any technical solutions formed by equivalent transformation or equivalent replacement shall fall within the protection scope of the present invention; some parts not elaborated in detail in the present invention belong to the known technologies of those skilled in the art.

Claims

1. A method for designing a cluster of unmanned boats that can gather and disperse, characterized in that: The method for designing a cluster of unmanned boats that can gather and disperse comprises the following steps: Step 1: Design the ship type with the purpose of reducing the total resistance and improving the seakeeping performance when the unmanned ship cluster sails in a formation combination mode; Step 2, design the connection device of the unmanned ship cluster; Step 3, design a parallel modular ship microgrid; Step 4, design the multi-boat power system and dynamics model; Step 5: Design the overall tracking control strategy for the unmanned ship cluster. In step 1, the following steps are also included: Step 11, the ship design adopts a rigidly connected following formation; Step 12, optimizing by adopting the principle of overall connection to improve seakeeping performance; Step 13, optimize using the principle of overall connection to reduce resistance.

2. The method for designing a cluster of unmanned boats that can gather and disperse according to claim 1 is characterized in that: In step 11, the rigidly connected following formation ships are embedded in each other's bow and stern during navigation, so that the bow of the rear ship can be inserted into the stern of the front ship when connected, and the grooves at the stern of the hull form a double stern, which makes the hull mass away from the center longitudinal line; Specifically, the stern of the hull is provided with a groove matching the shape of the bow to simultaneously reduce the friction resistance and pressure resistance generated by this part, so as to achieve the goal that the total resistance of the formation sailing is less than the sum of the total resistance of each ship sailing separately: R t编队 is the total resistance of formation sailing, R ti is the sailing resistance of the i-th hull in the formation, and n is the total number of hulls in the formation.

3. The method for designing a cluster of unmanned boats that can gather and disperse according to claim 1 is characterized in that: In step 12, the overall connection has the advantage of seakeeping; When the hull heels, the restoring moment is: Where M R is the restoring torque, It is the initial stability, which is related to the ship type, φ is the heel angle, and Δ is the displacement mass of the hull; After the whole is spliced, the cross section of the main part of the hull is the same as that of the single boat, so after the whole is spliced unchanged, since the displacement mass Δ of the hull increases exponentially after the whole splicing, the restoring moment M after splicing at the same heel angle φ R It is larger than a single boat and can resist greater wave interference after being spliced ​​as a whole, and has better seakeeping performance.

4. The method for designing a cluster of unmanned boats that can gather and disperse according to claim 1 is characterized in that: In step 13, the resistance advantage after the overall connection includes the friction resistance R f Advantages: When the hull moves, due to the viscosity of water, a boundary layer is formed around the hull, so that the hull is subjected to viscous shear stress during movement, that is, friction is generated on the surface of the hull. Its combined force in the direction of movement is the friction 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, is the velocity gradient; For the combined navigation condition of unmanned ship clusters, in the gap between the two ship hulls, the velocity gradient of the fluid boundary layer is affected by the wake of the hull. The shear stress of the fluid in the boundary layer of the hull at the connection between the two ships is very small, and it can be approximately considered that the surface area S of the underwater part of the multiple ships connected to the hull is 连接 The surface area S of the underwater part of a single ship is not taken into account. Compared with the dispersed navigation of unmanned ships, the surface area S of the underwater part of a single ship is reduced by (n-1)S. 连接 , hull friction resistance R f for: C f is the average friction resistance coefficient, v is the speed of the unmanned boat, S is the surface area of ​​the underwater part of the single boat, S 连接 It is the surface area of ​​the underwater part after multiple ships are connected.

5. The method for designing a cluster of unmanned boats that can gather and disperse according to claim 1 is characterized in that: In step 2, the connection device includes a hull connection device and a power connection device; The hull connection device is an electromagnetic adsorption device; The power connection device is a contact metal sheet arranged at the stern and the bow.

6. The method for designing a cluster of unmanned boats that can gather and disperse according to claim 1 is characterized in that: In step 3, the ship microgrid includes a power supply system, a control system, a sensing system, a power system, a front connection device and a rear connection device, and the connection between the components is in parallel, and the power supply system is used for power supply; The power supply system includes a power supply and a circulating current blocking diode connected in series. When multiple unmanned boat units are connected, due to the presence of the circulating current blocking diode, the power supply of multiple unmanned boats will be completely supplied by the side with a larger voltage, realizing the functions of redundant power supply and dispatching power distribution.

7. The method for designing a cluster of unmanned boats that can gather and disperse according to claim 1 is characterized in that: In step 4, each unmanned boat unit is equipped with two full-rotation thrusters in the middle and rear section of the hull, and the MMG maneuvering equation of the unmanned boat is: Where: m is the mass of the unmanned boat; m x and m y are the additional masses of the unmanned boat in the x-axis and y-axis directions respectively; I z and J z are the moment of inertia of the hull around the z-axis and the moment of inertia of the additional mass, respectively; u and v are the longitudinal velocity and transverse velocity of the ship, respectively; r is the angular velocity of the hull around the z-axis; are the accelerations derived from the longitudinal velocity, lateral velocity and angular velocity respectively; X H , Y H and N H are the longitudinal force, lateral force and bow moment of all external forces acting on the hull except the propeller; X P , Y P and N P are respectively the thrust, transverse force and bow pitch moment exerted by the propeller on the hull; The thrust generated by the thruster is: Where, T L is the thrust generated by the left thruster, T R 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 boat.

8. The method for designing a cluster of unmanned boats that can gather and disperse according to claim 7 is characterized in that: In step 4, the overall MMG maneuvering equation after multiple boats are connected is: Each thruster can generate thrust of different magnitudes and directions, and the overall control force is: T1~T6 are the thrusts generated by the six thrusters, α1~α6 are the rudder angles of the six steering gears, (x n ,y n ) is the position of the propeller relative to the center of gravity of the hull.

9. The method for designing a cluster of unmanned boats that can gather and disperse according to claim 1 is characterized in that: In step 5, after the three unmanned boat units are connected, the whole has six full-rotation thrusters, thrusters No. 1 and No. 2 are thrusters for the first unmanned boat in the front, thrusters No. 3 and No. 4 are thrusters for the second unmanned boat in the middle, and thrusters No. 5 and No. 6 are thrusters for the third unmanned boat in the back; during the overall tracking process, the rudder angles of thrusters No. 3 and No. 4 remain unchanged at 0, and the bow torque is achieved by controlling the rudder angles of the thrusters of the No. 1 unmanned boat unit and the No. 3 unmanned boat unit; When the unmanned boat is at a low speed, the first unmanned boat unit and the third unmanned boat unit have opposite directions after being connected, so as to obtain a larger bow turning moment and avoid the situation of insufficient bow turning; When the unmanned boat is at high speed, the first unmanned boat unit and the third unmanned boat unit have the same steering direction after being connected at high speed, so as to obtain a smaller bow turning torque and avoid excessive bow turning.

10. The method for designing a cluster of unmanned boats that can gather and disperse according to claim 9, characterized in that: In step 5, the rudder angle α1 of the first unmanned boat unit and the rudder angle α3 of the third unmanned boat unit are set to be proportional: α1＝kα3 Among them, k is the proportional coefficient, and its value is determined according to the speed v of the unmanned boat. The smaller the speed, the larger the rudder angle of the reverse rotation of the No. 1 unmanned boat unit, and the larger the speed, the larger the rudder angle of the forward rotation of the No. 1 unmanned boat unit; Set to when the overall maximum speed v mac , α1=α3, that is, k=1. When the overall maximum speed approaches 0, α1=-α3, that is, k=-1. The k value is set to change linearly with the speed v: Based on this rudder angle control strategy, a PID controller can be set to control the heading maintenance during the overall tracking process, similar to the heading control of a single boat.

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