Layered optimal distribution method for thrust of double water-jet propellers

Abstract

A double-water-jet-propeller thrust layered optimal distribution method comprises the steps that a basic unmanned ship double-water-jet-propeller mechanical model is constructed, a first-layer thrust distribution optimization model is obtained through an area division and vector synthesis method, a component thrust vector is solved, and first distribution is completed; second-time distribution is carried out under the condition of adding equality limitation between inverted buckets and thrust through a minimum distance method, and the inverted bucket angle of the double propellers and the corresponding main engine power are obtained; and finally, when a singularity phenomenon occurs in the second-layer distribution, the thrust distribution process is not intervened, and the nozzle flow velocity is directly and independently controlled, so that thrust optimization is realized. According to the method, the influence of propeller angle rotation rate limitation, bucket reversing rotation rate limitation and bucket reversing on thrust is considered at the same time, and the control precision and the control principle are optimized; the inverted bucket is more accurately controlled, the inverted bucket is brought into a thrust control loop, the convergence time when the propeller obtains the negative force is shortened, the power oscillation amplitude of a main engine can be controlled in the thrust size floating process of the propeller, and the shafting abrasion of the propeller is reduced.

Description

Technical Field

[0001] The present invention relates to a technology in the field of unmanned boats, in particular to a method for optimizing thrust distribution of double water jet propulsion units taking into account the reverse force of bucket dumping. Background Art

[0002] The existing water jet propulsion system and its thrust distribution have the following problems: first, the thrust range is discontinuous, resulting in a non-convex thrust range; second, the equation constraint relationship of the bucket on the thrust is nonlinear, making the constraint condition non-convex. Summary of the invention

[0003] In view of the problem that the existing thrust distribution technology is not suitable for the propulsion mode of dual water jet propulsion and cannot control the negative force of the bucket, the present invention proposes a dual water jet thrust stratified optimization distribution method, applies the idea of ​​stratified optimization, and considers the propeller angle rotation rate limit, the bucket rotation rate limit and the influence of the bucket on the thrust, and optimizes the control accuracy and control principle; through more precise control of the bucket, the bucket is incorporated into the thrust control, which shortens the convergence time of the propeller when the negative force is obtained, and can control the main engine power oscillation amplitude during the floating process of the propeller thrust size, thereby reducing the wear of the propeller shaft system.

[0001] The present invention is achieved through the following technical solutions:

[0002] The invention relates to a method for optimizing the layered thrust distribution of a dual water jet propulsion system. A basic mechanical model of a dual water jet propulsion system for an unmanned boat is constructed. A first-layer thrust distribution optimization model is obtained through regional division and vector synthesis method, and a thrust vector is obtained by solving the model to complete the first distribution. Then, a second distribution is performed under the condition of adding an equation restriction between the bucket and the thrust through a minimum distance method to obtain the bucket angle of the dual propulsion system and the corresponding main engine power. Finally, when a singularity phenomenon occurs in the second-layer distribution, the thrust distribution process is not intervened, and the nozzle flow rate is directly and individually controlled, thereby achieving thrust optimization.

[0003] The first-layer thrust distribution optimization model is as follows: min F,s F T F+s T Qs,stMF=τ+s, Where: i,j ≥0, i=1,2, j=1,2.

[0004] The present invention relates to a system for realizing the above method, comprising: an unmanned boat control system, a water jet propulsion, a communication device and a propeller control module, wherein: the unmanned boat control system solves and obtains the PWM signal and the electric control signal required by the propeller according to the propeller nozzle angle, the bucket angle and the propeller speed parameter instructions of the propellers on both sides output by the propeller control module; the water jet propulsion responds according to the signal output by the propeller control module, so that the propellers on both sides generate the expected thrust; the communication device receives the left and right propeller parameters output by the propeller control module, and feeds back the real-time propeller working conditions to the control system; the propeller control module performs the calculation at the next moment according to the required resultant force and the fed-back propeller parameters, obtains the expected propeller parameters, and sends them to the unmanned boat.

[0005] The unmanned boat control system includes: a motion controller and a power manager, wherein: the motion controller converts the instructions into PWM signals and electric control signals according to the instructions calculated by the thruster control module, sends them to the left and right thrusters, and monitors the speed, nozzle angle, and bucket angle data of the left and right thrusters in real time. The electric regulator controls the thruster to reach the specified speed according to the PWM signal. The power manager is responsible for powering all devices and recording voltage and current data in real time.

[0006] The water jet propulsion device comprises: a motor, blades, a nozzle and a bucket, wherein: the motor receives an electric adjustment current to make the blades rotate at an expected speed to generate a desired thrust; the nozzle adjusts the rotation angle according to an electric control signal, and changes the left and right direction of the thrust by changing the direction of the water flow; the bucket adjusts the rotation angle of the bucket according to the electric control signal, and affects the magnitude and positive and negative of the thrust by deflecting the water flow.

[0007] The thruster control module includes: a thrust distribution unit and a host computer unit, wherein: the thrust distribution unit calculates the expected speed value, nozzle angle value and bucket angle value of the thruster within the restriction conditions according to the resultant force and torque required by the unmanned boat, combined with the real-time speed, nozzle angle and bucket angle of the left and right thrusters; the host computer unit receives the calculation result of the thrust distribution unit and sends it to the unmanned boat, controls the left and right thrusters of the unmanned boat to achieve the expected data, and at the same time, receives the thruster data fed back by the unmanned boat in real time and sends it to the thrust distribution unit. Technical Effects

[0008] The present invention limits the rotation angle range of the propeller nozzle in the first-layer thrust distribution optimization model, ensures that the propeller nozzle angle will not exceed the rotation angle limit range under linear conditions, and adjusts the angle within the limited rate. At the same time, in the second-layer thrust distribution optimization model, the limit of the bucket rotation speed is added to deal with the particularity of the water jet propulsion in the rotation range, propulsion and reverse navigation principle, introduces the vector synthesis method, the area division method and the minimum distance method, and through the layered optimization method, under the condition of limiting the rotation range and rotation rate of the nozzle and the bucket, the thrust distribution of the dual water jet propulsion unmanned boat is realized, and a solution to the singular phenomenon is proposed. Compared with the existing thrust distribution method, the present invention can effectively take into account the negative force characteristics of the bucket, use the influence of the bucket on the thrust size, reduce the main engine power oscillation frequency and amplitude under the condition of thrust change, reduce the main engine wear, and improve the accuracy of the unmanned boat control process. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a flow chart of the present invention;

[0010] Figure 2 It is a system diagram of the present invention;

[0011] Figure 3 This is a diagram of the test equipment for verifying the present invention;

[0012] Figure 4 This is a schematic diagram of regional division;

[0013] Figure 5 It is a schematic diagram of the method for adjusting the flow rate of the thruster bucket and the nozzle when the thrust is expected to be stable;

[0014] Figure 6 It is a schematic diagram of the method for adjusting the flow rate of the propeller bucket and the nozzle when the bucket changes greatly;

[0015] Figure 7a Schematic diagram of the change of the angles of the left and right thrusters during the lateral movement in the embodiment;

[0016] Figure 7b Schematic diagram of the change of thrust magnitude of the thrusters on the left and right sides during the lateral movement in the embodiment;

[0017] Figure 8a Schematic diagram of the flow rate changes of the nozzles on the left and right sides in different distribution methods in the embodiment;

[0018] Figure 8b Schematic diagram comparing the change of bucket angles of the present invention and the method without control in the embodiment;

[0019] Fig. 9 Schematic diagram of the flow velocity change of the thruster nozzle before and after singularity processing;

[0020] Fig.10a This is a schematic diagram of the power changes of the left and right thrusters in the rotation condition test;

[0021] Fig.10b Schematic diagram of the power change of the left and right thrusters in the lateral movement test. DETAILED DESCRIPTION

[0022] like Figure 1 As shown, this embodiment relates to a dual water jet thrust layered optimization distribution method, comprising:

[0023] Step 1: Based on the structure and configuration of the dual water jet propulsion system on the unmanned boat, a basic dual water jet propulsion system mechanical model is constructed, including:

[0024] Step 1.1: Establish a mechanical model of the dual water jet propulsion system to ensure that the combined thrust of the two propulsion systems is equal to the required resultant force, specifically: τ = MF, where: the resultant force vector τ = [F x ,F y ,τ z ], the thrust of the two thrusters F = [F1 F2] T , F1 and F2 are the thrust vectors of each thruster, and their forms are F i =[F xi F yi ] T ,i=1,2, thruster configuration matrix

[0025] Step 1.2: The thrust distribution problem is summarized as an optimization problem, and a basic optimization function is constructed based on the mechanical model of the dual water jet propulsion system. The optimization goal is to minimize the propulsion power and maintain force balance. The optimization function expression is: min F, s F T F+s T Qs,stMF=τ+s, where: thrust quadratic term F T F represents the thruster power, s∈R 3 is a slack variable, which is used to ensure that the optimization function will obtain an optimal approximate solution when the exact solution cannot be obtained. The penalty term s T In Qs, Q is the weight matrix, which minimizes the relaxation factor.

[0026] Step 2: Introduce the idea of ​​regional division and vector synthesis method to solve the non-convex problem of thruster angle limitation in the mechanical model of dual water jet thrusters, including:

[0027] Step 2.1: Construct vector where θ i,old,i=1,2 is the nozzle rotation angle at the previous moment. Δθ max The nozzle represents the maximum change of the nozzle angle within a single control step. This value can be calculated by multiplying the maximum change rate of the nozzle angle by the control step time. The maximum change rate of the nozzle angle is related to the execution delay of the water jet propulsion mechanism and can be measured by the controlled water jet propulsion. In order to ensure that the nozzle angle is within the physical limit at the next moment, the rotation angle range of the propeller nozzle is limited. The maximum allowable angle of the nozzle angle in the positive direction is set to θ max , the maximum allowable negative angle θ min .

[0028] Step 2.2: Solve the problem of discontinuous change in thrust direction of water jet propulsion by regional division. Specifically, according to the thrust range characteristics of water jet propulsion, the entire plane is divided into four regions with the maximum rotatable angle of the nozzle as the boundary, such as Figure 4 After the required resultant force is input, the four regions are divided and the positive and negative of the thrusters on both sides are defined in advance, so that the thrust range on the other side of the thruster can be ignored, and the thrust vector synthesis constraint condition retains convexity.

[0029] Step 3: Consider the scenario where both thrusters are propelling forward, solve the first-level thrust distribution optimization model obtained in steps 1-2, and after obtaining the thrust vectors for distributing the required resultant force to the two thrusters, the two thrusters rotate to the required angles according to their respective vectors to complete the first distribution.

[0030] The first-layer thrust distribution optimization model is as follows: min F,s F T F+s T Qs,stMF=τ+s, Where: i,j ≥0, i=1,2, j=1,2.

[0031] Step 4: According to the minimum distance method, a second distribution is performed under the condition of adding the equation constraint between the bucket and the thrust, and the bucket angle of the dual thrusters and the corresponding thruster power are obtained, which specifically includes:

[0032] Step 4.1: Construct the thrust size and nozzle velocity v of the water jet propulsion system j , nozzle angle θ, ship speed u and bucket angle γ, and then derive the relationship between the thrust of a single propeller and its nozzle flow rate and its bucket angle, specifically: F x =ρA j v j (v j cosθ-u)·cosγ, where: ρ is the fluid density, Aj is the nozzle area, and both are constants. The nozzle angle θ has been obtained from the above step 3.1. The longitudinal speed u of the ship is obtained in real time by the sensor during the driving process of the unmanned boat and can be regarded as a known quantity. Let F x / cosθ·ρA j =F, the relationship between the thrust of a single propeller, its nozzle velocity and its bucket angle is: Where: u / cosθ=e is a known number; nozzle velocity v j The angle γ of the bucket is satisfied: The nozzle flow rate v j With the bucket angle γ as the coordinate axis, a two-dimensional plane is constructed. The nozzle velocity value and the bucket angle value of the water jet propulsion device at each moment can find corresponding points in the plane. For example, assuming that the propulsion device needs to generate thrust F1 at a certain moment, substitute F1 into formula (9), and we have That is, the bucket angle γ is related to the nozzle flow velocity v j function curve, any point on the curve (v j ,γ), the thruster can generate the target thrust F1. Therefore, it is only necessary to change the thruster state point (v j ,γ) can be moved to the function curve corresponding to the target thrust in some way, so that the thruster can produce the target thrust with the optimal combination of nozzle flow rate and bucket angle.

[0033] Step 4.2: Scale the longitudinal axis of the two-dimensional plane of the nozzle velocity and the bucket angle in step 4.1, and ignore the known quantity e whose value is related to the ship state. The function expression after scaling with the scaling coefficients ξ1 and ξ2 on both sides should be: When the required thrust changes, the thruster searches for the position closest to the initial state in the direction of the function curve determined by the function expressions on both sides, allowing the bucket to participate in the thrust change process.

[0034] Step 4.3: In the process of solving the vertical point, multiple solutions may appear. When multiple solutions appear, set the horizontal coordinate v of the corresponding point of the thruster state j The horizontal coordinate v of the i-th vertical point found with the corresponding point ji The difference is dv ji , the vertical coordinate of the point corresponding to the thruster state γξ m ,m=1,2 and the vertical coordinate γ of the i-th vertical point i ξ m ,m=1,2 The difference is dγ i Based on the idea of ​​balancing the propeller power adjustment and the bucket angle adjustment, the solution with similar adjustment ranges of the nozzle flow rate and the bucket angle is preferred, that is, dv ji +dγ iThe corresponding solution when the maximum value is taken. Therefore, the solution of the vertical point can be summarized as the optimization problem (11):

[0035] Preferably, during the solution process of steps 4.2-4.3, when the subsequent thrust does not change, or the change range is small, the target thrust corresponding curve will also remain unchanged or almost unchanged. Then when the nozzle flow rate of the propeller and the bucket angle have been adjusted to the curve along the vertical line corresponding to the minimum distance direction, the propeller state will no longer change, so that the bucket remains at a certain angle, resulting in power waste. Therefore, when the difference between the bucket angle and the optimal solution bucket angle is less than the set limit, it is considered that the propeller has entered a stable state, and the corresponding point of the propeller state is limited to the maximum speed of the bucket angle adjustment. According to the positive and negative thrust of the propeller at this time, it is gradually adjusted to the maximum or minimum value of the bucket angle. The schematic diagram of the specific adjustment method is shown as follows. Figure 5 shown.

[0036] Preferably, the bucket rotation process needs to be limited by the rotation rate. When the bucket angle is significantly different from the expected angle, the bucket needs to execute the process time to rotate to the expected angle. During this process, it is impossible to adjust the propeller speed according to the bucket angle in the intermediate state to ensure that the target thrust is generated at every moment. Therefore, when the bucket cannot rotate to the expected angle within a single time step, the corresponding point of the propeller state is set to the maximum change value Δγ of the bucket angle within a single control step. max To limit the rotation towards the target, Figure 6 At the same time, during the bucket rotation process, according to the vertical line corresponding to the minimum distance obtained by the second-level optimization process, the bucket angle value of each step is substituted into the vertical line to determine the nozzle flow rate value, which can limit the bucket rotation rate and ensure the stability of the propeller power during the bucket rotation process.

[0037] Step 5. According to the left and right thruster nozzle flow rates and the bucket angle results obtained in step 4, control the simulation object to perform specific execution, and control the nozzle flow rate separately in the second distribution to deal with the singularity phenomenon that may occur in the distribution process, that is, in the thrust distribution process, when the longitudinal force or lateral force required by the unmanned boat at a certain point in time is not a small amount, but the thrust of the thruster solved by the distribution is a small amount, specifically: when a singularity phenomenon occurs, do not intervene in the thrust distribution process, and directly fix the main engine power and the bucket angle of the lower layer, so as to ensure the stability of the main engine power when a singularity phenomenon occurs in the thrust distribution, and ensure the stability of the system.

[0038] Assume that the configuration data of the unmanned boat propulsion system is l x1 = l x2 = l x =-2, l y1 =-l y2 = ly =1, and set two working conditions, including:

[0039] Working condition 1) The unmanned boat performs a variable speed lateral movement, that is, the longitudinal speed and total torque are kept zero, and the required lateral force expression is set to F y =100sin(πt / 5)N, distribute the thrust to the target resultant force and verify the distribution effect of the algorithm.

[0040] Working condition 2) Assuming that the unmanned boat is subject to the time-varying environmental interference force during the vector motion, in order to ensure stable vector motion, the water jet propulsion system needs to generate a corresponding force to resist the time-varying environmental interference force. The following three simulations are set: Simulation 1: Set the target vector motion of the unmanned boat to lateral motion, assuming that the lateral motion is subject to a time-varying environmental interference force between 50N and 100N. Simulation 2: Set the target vector motion of the unmanned boat to lateral motion, assuming that the lateral motion is subject to a time-varying environmental interference force between 25N and -100N. Simulation 3: Set the target vector motion of the unmanned boat to in-situ rotation motion, assuming that the rotation motion is subject to a time-varying environmental interference torque between 100N·m and -200N·m.

[0041] According to the above-mentioned propeller settings and target working conditions, through simulation experiments, the nozzle flow rate, nozzle angle and bucket angle change diagrams of the two propellers were obtained. According to Figure 7, the distribution effect of this design distribution method is good, and the nozzle angle can be controlled to rotate to the target angle at the maximum rate and remain stable; according to Figure 8, this method can rotate the bucket in time when the thrust of the propeller oscillates. Compared with other thrust distribution methods that do not consider the influence of the bucket on the thrust, the rotation of the bucket can reduce the oscillation frequency and amplitude of the main engine power; according to Fig. 9 It can be seen that when strange phenomena occur in the thrust distribution system, the stability of the main engine power can be improved and the shaft wear can be reduced.

[0042] After specific actual tests, the above method was run on a ship model with a length of 3m and a width of 0.85m. The working condition settings were the same as those of simulation 1 and simulation 3. The lateral working condition was set as follows: the unmanned boat lateralized to the left, that is, the longitudinal force and torque were both kept at zero, and the initial lateral force was 20N. At the 10th second, the lateral force increased from 20N to 40N. From the 13th second, the lateral force began to oscillate between 20N and 40N, with an oscillation frequency of 1 time / s, and stopped at the 17th second. The rotation working condition was set as follows: the unmanned boat performed an in-situ rotation motion, that is, the lateral force and longitudinal force were both kept at zero, and the initial torque was 12.5N·m. At the 9th second, the torque increased from 12.5N·m to 25N·m, waiting for the thruster to enter a stable state. From the 13th second, the torque oscillated between 12.5N·m and 25N·m at a frequency of once every 2s, and stopped at the 19th second. The experimental data that can be obtained are shown in Figure 10, where Fig.10a The power changes of the left and right thrusters in the lateral working condition are as follows: Fig.10b The power changes of the left and right thrusters under the rotation condition.

[0043] Compared with the prior art, the semi-physical simulation test results of the above two working conditions show that the present invention can respond to the changes in instructions in a timely manner and in accordance with the expected changes, regardless of whether it is a lateral movement condition or a rotation condition. On this basis, the present invention can delay the time required for the descent process to more than 1 second when the power needs to change significantly. Under the condition of the resultant force or torque oscillation of the unmanned boat, the power change amplitude of the forward thrust propeller under this condition can be reduced by a certain amplitude, and the power reduction speed can be effectively slowed down, the main engine power can be stabilized, and it has the advantages of controlling the main engine power adjustment frequency and reducing shaft wear.

[0044] The above-mentioned specific implementation can be partially adjusted in different ways by those skilled in the art without departing from the principle and purpose of the present invention. The protection scope of the present invention shall be based on the claims and shall not be limited by the above-mentioned specific implementation. Each implementation scheme within its scope shall be subject to the constraints of the present invention.

Claims

1. A method for optimizing thrust distribution of dual water jet propulsion units by layering, characterized in that: By constructing a basic mechanical model of the unmanned boat's twin water jet propulsion, the first-layer thrust distribution optimization model is obtained through regional division and vector synthesis method, and the thrust vector is solved to complete the first distribution; then the second distribution is carried out through the minimum distance method under the added equation constraint condition between the bucket and the thrust, and the bucket angle of the twin thrusters and the corresponding main engine power are obtained; finally, when singularity occurs in the second-layer distribution, the thrust distribution process is not intervened, and the nozzle flow rate is directly controlled individually to achieve thrust optimization.

2. The method for optimizing thrust distribution of dual water jet propulsion units according to claim 1 is characterized in that: The first-layer thrust distribution optimization model is as follows: min F,s F T F+s T Qs,stMF=τ+s,F i =λ i,1 v1+λ i,2 v2, Where: i,j ≥0, i=1,2, j=1,2.

3. The method for optimizing thrust distribution of dual water jet propulsion according to claim 1 or 2, characterized in that: include: Step 1: Based on the structure and configuration of the dual water jet propulsion system on the unmanned boat, a basic dual water jet propulsion system mechanical model is constructed, including: Step 1.1: Establish a mechanical model of the dual water jet propulsion system to ensure that the combined thrust of the two propulsion systems is equal to the required resultant force, specifically: τ = MF, where: the resultant force vector τ = [F x ,F y ,τ z ], the thrust of the two thrusters F = [F1 F2] T , F1 and F2 are the thrust vectors of each thruster, and their forms are F i =[F xi F yi ] T ,i=1,2, thruster configuration matrix Step 1.2: The thrust distribution problem is summarized as an optimization problem, and a basic optimization function is constructed based on the mechanical model of the dual waterjet propulsion system. The optimization goal is to minimize the propulsion power and maintain force balance. The optimization function expression is: min F,s F T F+s T Qs,stMF=τ+s, where: thrust quadratic term F T F represents the thruster power, s∈R 3 is a slack variable, which is used to ensure that the optimization function will obtain an optimal approximate solution when the exact solution cannot be obtained. The penalty term s T In Qs, Q is the weight matrix, which minimizes the relaxation factor; Step 2: Introduce the idea of ​​regional division and vector synthesis method to solve the non-convex problem of thruster angle limitation in the mechanical model of dual water jet thrusters, including: Step 2.1: Construct vector where θ i,old , i=1,2 is the nozzle rotation angle at the previous moment, Δθ max The nozzle represents the maximum change of the nozzle angle within a single control step time. This value can be calculated by multiplying the maximum change rate of the nozzle angle by the control step time. The maximum change rate of the nozzle angle is related to the execution delay of the water jet propulsion mechanism and can be obtained by actual measurement of the controlled water jet propulsion. In order to ensure that the nozzle angle is within the physical limit at the next moment, the rotation angle range of the propeller nozzle is limited. The maximum allowable angle of the nozzle angle in the positive direction is set to θ max , the maximum allowable negative angle θ min ; Step 2.2, solve the problem of discontinuous change of thrust direction of water jet propulsion by regional division, specifically: according to the thrust range characteristics of water jet propulsion, the entire plane is divided into four regions with the maximum rotatable angle of the nozzle as the boundary. After the required resultant force is input, the four regions are divided and the positive and negative of the thrusters on both sides are defined in advance, so that the thrust range of the other side of the thruster can be ignored, so that the vector synthesis constraint condition of the thrust retains convexity; Step 3: Consider the scenario where both thrusters are forward thrusting, solve the first-layer thrust distribution optimization model obtained in step 1-2, and after obtaining the thrust vectors of the required resultant force distributed to the two thrusters, the two thrusters rotate to the required angles according to their respective vectors to complete the first distribution; Step 4: According to the minimum distance method, a second distribution is performed under the condition of adding the equation constraint between the bucket and the thrust, and the bucket angle of the dual thrusters and the corresponding thruster power are obtained; Step 5. According to the left and right thruster nozzle flow rates and the bucket angle results obtained in step 4, control the simulation object to perform specific execution, and control the nozzle flow rate separately in the second distribution to deal with the singularity phenomenon that may occur in the distribution process. That is, in the thrust distribution process, when a singularity phenomenon occurs, do not intervene in the thrust distribution process, and directly fix the main engine power and the bucket angle of the lower layer, so as to ensure the stability of the main engine power when a singularity phenomenon occurs in the thrust distribution, and ensure the stability of the system.

4. The method for optimizing thrust distribution of dual water jet propulsion units according to claim 3 is characterized in that: The step 4 specifically includes: Step 4.1: Construct the thrust size and nozzle velocity v of the water jet propulsion system j , nozzle angle θ, ship speed u and bucket angle γ, and then derive the relationship between the thrust of a single propeller and its nozzle flow rate and its bucket angle, specifically: F x =ρA j v j (v j cosθ-u)·cosγ, where: ρ is the fluid density, A j is the nozzle area, and both are constants. The longitudinal speed u of the ship is obtained in real time by the sensor during the driving process of the unmanned boat. x / cosθ·ρA j =F, the relationship between the thrust of a single propeller, its nozzle velocity and its bucket angle is: Where: u / cosθ=e is a known number; nozzle velocity v j The angle γ of the bucket is satisfied: The nozzle flow rate v j With the bucket angle γ as the coordinate axis, a two-dimensional plane is constructed, and the nozzle flow rate value and the bucket angle value of the water jet propulsion device at each moment have corresponding points in the plane; Step 4.2: Scale the vertical axis of the two-dimensional plane of the nozzle velocity and the bucket angle in step 4.1, and ignore the known quantity e related to the ship state, and obtain the function expression γ·ξ after scaling with the scaling coefficients ξ1 and ξ2 on both sides: m =arccos(F / v j 2 ),m=1,2; when the required thrust changes, the thruster searches for the position with the shortest distance from the initial state to the direction of the function curve determined by the function expressions on both sides; Step 4.3: When multiple solutions appear in the process of solving the vertical point, the solution of the vertical point is summarized as an optimization problem: Where: The horizontal coordinate v of the point corresponding to the thruster state j The horizontal coordinate v of the i-th vertical point found with the corresponding point ji The difference is dv ji , the vertical coordinate of the point corresponding to the thruster state γξ m ,m=1,2 and the vertical coordinate γ of the i-th vertical point i ξ m ,m=1,2 The difference is dγ i .

5. The method for optimizing thrust distribution of dual water jet propulsion units according to claim 4 is characterized in that: When the difference between the bucket angle and the optimal solution bucket angle is less than the set limit, the thruster is considered to have entered a stable state. The corresponding point of the thruster state is limited to the maximum speed of the bucket angle adjustment. Depending on the positive or negative thrust of the thruster at this time, the angle is gradually adjusted to the maximum or minimum value.

6. The method for optimizing thrust distribution of dual water jet propulsion units according to claim 4 is characterized in that: When the bucket cannot rotate to the expected angle within a single time step, the corresponding point of the thruster state is set to the maximum change value Δγ of the bucket angle within a single control step. max In order to limit the rotation toward the target, during the bucket rotation process, the bucket angle value of each step is substituted into the vertical line corresponding to the minimum distance obtained by the second-level optimization process to determine the nozzle flow rate value.

7. A dual water jet thrust layered optimization distribution system for implementing any of the methods described in claims 1-6, characterized in that: include: An unmanned boat control system, a water jet propulsion system, a communication device and a propeller control module, wherein: the unmanned boat control system obtains the PWM signal and the electric control signal required by the propeller according to the propeller nozzle angle, the bucket angle and the propeller speed parameter instructions of the two sides of the propeller output by the propeller control module; the water jet propulsion system responds according to the signal output by the propeller control module to make the propellers on both sides generate the expected thrust; the communication device receives the left and right propeller parameters output by the propeller control module, and feeds back the real-time propeller working conditions to the control system; the propeller control module performs calculations at the next moment according to the required resultant force and the fed-back propeller parameters, obtains the expected propeller parameters, and sends them to the unmanned boat.

8. The dual water jet thrust layered optimization distribution system according to claim 7 is characterized in that: The unmanned boat control system includes: a motion controller and a power manager, wherein: the motion controller converts the instructions into PWM signals and electric control signals according to the instructions calculated by the thruster control module, sends them to the left and right thrusters, and monitors the speed, nozzle angle, and bucket angle data of the left and right thrusters in real time. The electric regulator controls the thruster to reach the specified speed according to the PWM signal. The power manager is responsible for powering all devices and recording voltage and current data in real time.

9. The dual water jet thrust layered optimization distribution system according to claim 7 is characterized in that: The water jet propulsion device comprises: a motor, blades, a nozzle and a bucket, wherein: the motor receives an electric adjustment current to make the blades rotate at an expected speed to generate a desired thrust; the nozzle adjusts the rotation angle according to an electric control signal, and changes the left and right direction of the thrust by changing the direction of the water flow; the bucket adjusts the rotation angle of the bucket according to the electric control signal, and affects the magnitude and positive and negative of the thrust by deflecting the water flow.

10. The dual water jet thrust layered optimization distribution system according to claim 7 is characterized in that: The thruster control module includes: a thrust distribution unit and a host computer unit, wherein: the thrust distribution unit calculates the expected speed value, nozzle angle value and bucket angle value of the thruster within the restriction conditions according to the resultant force and torque required by the unmanned boat, combined with the real-time speed, nozzle angle and bucket angle of the left and right thrusters; the host computer unit receives the calculation result of the thrust distribution unit and sends it to the unmanned boat, controls the left and right thrusters of the unmanned boat to achieve the expected data, and at the same time, receives the thruster data fed back by the unmanned boat in real time and sends it to the thrust distribution unit.

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