Modeling method of dynamic model for safety test simulation of unmanned ship

Abstract

The invention discloses a dynamic model modeling method for unmanned ship safety test simulation, and relates to the technical field of unmanned ship safety test simulation. According to the method, a dynamic model of the unmanned ship is simplified, and a roll angle change second-order model driven by roll torque is modeled by combining a speed hydrodynamic parameter table and a speed-steering roll angle relation according to special requirements of roll and pitching dynamic response; a pitch angle change second-order model driven by pitch moment is modeled by combining a speed hydrodynamic parameter table and a speed-pitch angle relation, and the pitch angle change second-order model driven by the pitch moment is modeled only by utilizing the easily obtained thrust-speed of the real unmanned ship, the advancing direction speed-steering roll angle relation in the steering process and the speed-pitch angle relation; therefore, the rolling and pitching dynamic response relation of the unmanned ship can be fitted and established, the complete unmanned ship dynamic model is established, the modeling process of the unmanned ship dynamic model is simplified and decoupled, and the calculation speed and simulation fitting accuracy of the unmanned ship dynamic model are improved.

Description

Technical Field

[0001] This invention relates to the field of unmanned surface vessel (USV) safety testing and simulation technology, and in particular to a dynamic modeling method for USV safety testing and simulation. Background Technology

[0002] Currently, in the safety testing phase of unmanned surface vessel (USV) intelligent control systems, after receiving target information or desired output, the perception and control algorithms generate control inputs that act on the controlled object (USV). The effectiveness of the control, perception, and decision-making algorithms is verified by observing the USV's trajectory and state. Due to the complex and variable nature of marine conditions, conducting actual safety tests under various conditions is costly and dangerous. Therefore, testing through a hardware-in-the-loop (HIL) intelligent control system platform can minimize testing costs and risks. This requires a highly accurate simulation model of the controlled object's dynamics as an intermediate medium for control inputs and outputs.

[0003] Existing unmanned surface vessel (USV) dynamics models provide detailed models of the inertia matrix, Coriolis force-centripetal force matrix, and restoring force matrix based on different vessel types. When considering wind and wave forces, the moment relationship matrices have high dimensionality and order, and high coupling in various directions, requiring extensive data collection to fit the relevant parameters. However, the number of times USVs have been tested in real-world scenarios such as at sea and on lakes is limited, resulting in insufficient data collection and characteristic description information. Consequently, existing USV dynamics models have poor adaptability to real-world USV navigation data.

[0004] In summary, existing unmanned surface vessel (USV) dynamics models are characterized by strong nonlinearity and high coupling, which leads to problems such as slow dynamics model calculations and inaccurate simulation fitting. Summary of the Invention

[0005] Therefore, it is necessary to provide a dynamic modeling method for unmanned surface vessel safety testing simulation to address the above-mentioned technical problems.

[0006] The present invention adopts the following technical solution: This invention provides a dynamic modeling method for unmanned surface vessel (USV) safety testing simulation, comprising: The initial simulation parameters for the safety test simulation of the unmanned surface vessel (USV) are obtained, and the global pose of the USV on the nautical chart is determined. The initial simulation parameters include USV information and wave information. Based on the unmanned surface vessel's propulsion method, control data of the unmanned surface vessel is acquired. Based on the unmanned surface vessel information and wave information, the driving force and torque of the unmanned surface vessel in various dimensions under the control data are determined. Based on wave information and the global pose of the unmanned surface vessel (USV) on the nautical chart, the relative wave height of the USV's center point is determined in order to determine the torque of the waves on the USV in various dimensions. Based on the information of the unmanned surface vessel (USV), its global pose, the driving force and torque of the USV in various dimensions under the control data, the torque of the waves on the USV in various dimensions, and the fitting results of the USV's steering and pitch characteristics, a dynamic model is constructed and solved to determine the acceleration, velocity, and position of the USV in various dimensions. Specifically, the steering characteristic fitting result of the unmanned surface vessel (USV) is obtained by modeling a second-order model of roll angle change driven by roll moment based on the USV's speed-hydrodynamic parameter table and speed-steering roll angle relationship, in order to fit the USV's steering characteristics; the pitch characteristic fitting result of the USV is obtained by modeling a second-order model of pitch angle change driven by pitch moment based on the USV's speed-hydrodynamic parameter table and speed-pitch angle relationship, in order to fit the USV's pitch characteristics.

[0007] Optionally, the unmanned surface vessel (USV) information includes: the USV's initial position, initial attitude, shape, and mass; The wave information includes the wave speed, amplitude, frequency, wavelength, and direction.

[0008] Optionally, the unmanned surface vessel (USV) is a dual-jet pump monohull USV; the control data includes: left jet pump throttle, right jet pump throttle, left jet pump rudder direction, right jet pump rudder direction, left tipping bucket feed rate, and right tipping bucket feed rate; The process of determining the driving force and torque of the unmanned surface vessel (USV) in various dimensions under control data based on USV information and wave information specifically includes: Establish a coordinate system with the direction of the unmanned surface vessel's movement as the positive X-axis, according to the right-hand rule; When the rudder direction of the left injection pump is 0, the thrust in the X-axis direction generated by the throttle of the left injection pump is determined by the following formula: Fxl = LF·((0.65·lk) + 350) / 1000; When the right injection pump rudder direction is 0, the thrust in the X-axis direction generated by the right injection pump throttle is determined by the following formula: Fxr = RF·((0.65·rk) + 350) / 1000; When the rudder direction of the left injection pump changes, the X-axis thrust and Y-axis thrust generated by the throttle of the left injection pump are determined by the following formula: Ftl = LF·(lk+1000) / 2000; Freverse_l= LF·0.3·(1000-lk) / 2000; Fxl = cos(lj)·(Ftl - Freverse_l); Fyl = sin(lj)·(Ftl + Freverse_l); When the rudder direction of the right injection pump changes, the X-axis thrust and Y-axis thrust generated by the throttle of the right injection pump are determined by the following formula: Ftr = RF·(rk+1000) / 2000; Freverse_r = RF·0.3·(1000-rk) / 2000; Fxr = cos(rj)·(Ftr - Freverse_r); Fyr = sin(rj)·(Ftr + Freverse_r); Based on the thrust generated in each direction by the left and right jet pump throttles, the resultant force of the unmanned surface vessel in each direction is determined by the following formula: F_x = (Fxr + Fxl)·cos(pitch); F_y = (Fyr + Fyl)·cos(roll); F_z = (Fxr + Fxl)·sin(pitch)·cos(roll) - (Fyr + Fyl)·sin(roll); The pitch moment of the unmanned surface vessel is determined by the following formula: Np = - sign(pitch)·Z·cos(pitch)·ship_l / 8; If both the left and right jet pump rudder directions are not zero and the thrust in the X-axis direction generated by the left and right jet pump throttles is opposite, then the yaw moment of the unmanned surface vessel is determined by the following formula: M_rudder = (Fyr + Fyl)·ship_l / 2; otherwise, the yaw moment of the unmanned surface vessel is determined by the following formula: M_rudder = (Fxl - Fxr)·ship_w / 2; The roll moment of the unmanned surface vessel is determined by the following formula: Nr = (Fyr + Fyl)·0.5·ship_h; Wherein, Fxl is the X-axis thrust generated by the left injection pump throttle, LF is the maximum thrust output by the left injection pump, lk is the left bucket feed, Fxr is the X-axis thrust generated by the right injection pump throttle, RF is the maximum thrust output by the right injection pump, rk is the right bucket feed, Ftl is the corresponding thrust output by the left injection pump under the control of the left bucket feed, Freverse_l is the reaction thrust generated by the left bucket, lj is the yaw angle of the left bucket, and Ftr is the corresponding thrust output by the right injection pump under the control of the right bucket feed. The thrust is defined as follows: Freverse_r is the reaction thrust generated by the right tipping bucket, rj is the yaw angle of the right tipping bucket, pitch is the pitch angle of the unmanned surface vessel (USV), roll is the roll angle of the USV, Fyr is the thrust in the Y-axis direction generated by the right jet pump throttle, Fyl is the thrust in the Y-axis direction generated by the left jet pump throttle, F_x is the resultant force of the USV in the X-axis direction, F_y is the resultant force of the USV in the Y-axis direction, F_z is the resultant force of the USV in the Z-axis direction, Np is the pitch moment of the USV, sign() represents the sign function, ship_l is the length of the USV, M_rudder is the rotational torque generated by the dual jet pumps on the USV, ship_w is the width of the USV, Nr is the roll moment of the USV, and ship_h is the height of the USV.

[0009] Optionally, determining the relative wave height of the unmanned surface vessel's center point based on wave information and the unmanned surface vessel's global pose on the nautical chart specifically includes: Based on the wave speed, amplitude, global angle, and frequency, as well as the unmanned surface vessel's global pose on the nautical chart, the relative wave height of the unmanned surface vessel's center point is determined using the following formula: h(xyt)=Asin(wave_w / wave_vel)[(xcosθ + ysinθ) - wave_w·t + wave_theta]; Where h(xyt) is the relative wave height of the UAV's center point, A is the wave amplitude, wave_w is the wave frequency, wave_vel is the wave velocity, x is the X-axis coordinate of the UAV's global pose on the nautical chart, y is the Y-axis coordinate of the UAV's global pose on the nautical chart, θ is the global angle of the wave direction, t is time, and wave_theta is the initial phase angle of the wave.

[0010] Optionally, determining the torque of the ocean waves on the unmanned surface vessel in each dimension specifically includes: The area of ​​the sea surface occupied by the unmanned surface vessel is divided into grids, and for each grid area, the global position of that grid area on the nautical chart is determined. The water level of the grid area is determined based on the speed, amplitude, global angle and frequency of the waves, as well as the global position of the grid area on the nautical chart. The moment exerted by the waves in the grid area on the unmanned surface vessel's buoyancy, roll, and pitch is determined based on the water level height in that grid area. By summing up the moments of the waves in each grid area on the unmanned surface vessel's buoyancy, roll, and pitch, the moments of the waves on the unmanned surface vessel in each dimension are obtained.

[0011] Optionally, obtaining the speed-hydrodynamic parameter table of the unmanned surface vessel specifically includes: Within the throttle range of the unmanned surface vessel (USV), for each preset throttle, the speed of the USV when it accelerates to uniform linear motion under the corresponding thrust at that throttle in still water is obtained. Based on the relationship between the thrust corresponding to each throttle position and the speed of the unmanned surface vessel (USV) when it accelerates to uniform linear motion, a table of velocity-hydrodynamic parameters for the USV is established.

[0012] Optionally, the step of modeling a second-order model of the roll angle change driven by the roll moment based on the unmanned surface vessel's speed-hydrodynamic parameter table and speed-steering roll angle relationship, fitting the steering characteristics of the unmanned surface vessel, and determining the fitting result of the steering characteristics of the unmanned surface vessel specifically includes: Based on the unmanned surface vessel's speed-hydrodynamic parameter table, obtain the steady-state speed values ​​of the unmanned surface vessel after full rudder turn at different speeds in the forward direction. Based on the steady-state values ​​of the forward velocity after full rudder turn at different forward velocities of the unmanned surface vessel (USV) and the relationship between the USV's velocity and the roll angle, a second-order model of roll angle variation driven by roll torque is established. The first damping parameter in the second-order model of roll angle variation is calibrated by using the final value theorem of the Laplace transform of the second-order system, and the correspondence between the forward velocity of the unmanned surface vessel and the first damping parameter is obtained, which serves as the fitting result of the steering characteristics of the unmanned surface vessel.

[0013] Optionally, the step of modeling a second-order model of pitch angle variation driven by pitch moment based on the unmanned surface vessel's speed-hydrodynamic parameter table and speed-pitch angle relationship to fit the pitch characteristics of the unmanned surface vessel specifically includes: Based on the unmanned surface vessel's speed-hydrodynamic parameter table, obtain the steady-state speed values ​​of the unmanned surface vessel after full rudder turn at different speeds in the forward direction. Based on the steady-state velocity of the unmanned surface vessel (USV) after full rudder turn at different velocities in its forward direction and the velocity-pitch angle relationship of the USV, a second-order model of pitch angle variation driven by pitch moment is established. The second damping parameter in the second-order model of roll angle variation is calibrated by using the final value theorem of the Laplace transform of the second-order system, and the correspondence between the forward velocity of the unmanned surface vessel and the second damping parameter is obtained, which serves as the fitting result of the pitch characteristics of the unmanned surface vessel.

[0014] This invention provides a dynamic modeling device for unmanned surface vessel safety testing simulation, comprising: The acquisition module is used to acquire the initial simulation parameters for the unmanned surface vessel (USV) safety test simulation and determine the global pose of the USV on the nautical chart; the initial simulation parameters include USV information and wave information. The control module is used to acquire control data of the unmanned surface vessel (USV) based on its propulsion method, and to determine the driving force and torque of the USV in various dimensions under the control data based on USV information and wave information. The wave impact module is used to determine the relative wave height of the UAV's center point based on wave information and the UAV's global pose on the nautical chart, so as to determine the torque of the waves on the UAV in various dimensions. The dynamics solution module is used to construct a dynamic model based on the unmanned surface vessel (USV) information, global pose, driving forces and torques of the USV in various dimensions under the control data, torques of the waves on the USV in various dimensions, and fitting results of the USV's steering and pitch characteristics to determine the acceleration, velocity, and position of the USV in various dimensions. Specifically, the steering characteristic fitting result of the unmanned surface vessel (USV) is obtained by modeling a second-order model of roll angle change driven by roll moment based on the USV's speed-hydrodynamic parameter table and speed-steering roll angle relationship, in order to fit the USV's steering characteristics; the pitch characteristic fitting result of the USV is obtained by modeling a second-order model of pitch angle change driven by pitch moment based on the USV's speed-hydrodynamic parameter table and speed-pitch angle relationship, in order to fit the USV's pitch characteristics.

[0015] This invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the aforementioned dynamic modeling method for unmanned surface vessel safety test simulation.

[0016] The present invention provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the above-mentioned dynamic modeling method for unmanned surface vessel safety test simulation.

[0017] The above-mentioned at least one technical solution adopted in this invention can achieve the following beneficial effects: To address the need for simulation software to accurately reflect the motion of unmanned surface vessels (USVs) during navigation, particularly the rapid and realistic changes in pitch and roll angles caused by thrust control variations, traditional high-order dynamic modeling methods require extensive data acquisition to fit the dynamic response of actual USVs. This approach is characterized by difficulties in data acquisition, slow processing speed, and complex multidimensional fitting. This invention simplifies the dynamic model of unmanned surface vessels (USVs). Addressing the specific requirements of roll and pitch dynamic responses, it proposes a second-order model for roll angle variation driven by roll moment, combining speed-hydrodynamic parameter tables and speed-turning roll angle relationships; and a second-order model for pitch angle variation driven by pitch moment, combining speed-hydrodynamic parameter tables and speed-pitch angle relationships. Utilizing readily available data on the actual USV's thrust-speed, forward direction speed-turning roll angle relationships during turning, and speed-pitch angle relationships, the roll and pitch dynamic response relationships of the USV can be fitted and established, creating a complete USV dynamic model. This simplifies and decouples the USV dynamic model modeling process, improving the calculation speed and simulation fitting accuracy of the USV dynamic model. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0019] Figure 1 A schematic diagram of the dynamic modeling method for unmanned surface vessel safety testing simulation provided by the present invention; Figure 2 A schematic diagram of the hardware-in-the-loop simulation platform for security testing provided by this invention; Figure 3 A schematic diagram illustrating the connection relationships of various parts within a dynamics simulation module provided by this invention; Figure 4 A schematic diagram of the damping mapping relationship of a second-order velocity-roll model provided by the present invention; Figure 5 A schematic diagram illustrating the relationship between speed and pitch angle provided by the present invention; Figure 6 A schematic diagram of a UI interface provided by the present invention; Figure 7 A schematic diagram of a dynamic modeling device for unmanned surface vessel safety testing simulation provided by the present invention; Figure 8 A schematic diagram of a computer device for implementing a dynamic model modeling method for unmanned surface vessel safety testing simulation provided by the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0021] Currently, mainstream dynamic models cannot fully reflect the impact of natural factors such as wind, waves, and currents on unmanned surface vessels (USVs) in the marine environment. These external disturbances can lead to significant deviations between model predictions and actual motion. Furthermore, the characteristics of water currents vary greatly across different sea areas, making it difficult to build a universally applicable model. Moreover, to facilitate analysis and control design, dynamic models are often simplified during simulation applications. However, simplified models may not accurately reflect the actual behavior of USVs, especially when precise control is required. Finding a suitable balance between model complexity and computational efficiency is a crucial issue in dynamic modeling. In addition, in actual operation, model parameters may change over time, and the hydrodynamics and attitude angles of the USV will change with different speeds.

[0022] Therefore, for unmanned surface vessel (USV) safety simulation, a dynamic model needs to be developed that meets the following four requirements: First, the model construction needs to be sufficiently accurate and consider major environmental influencing factors. This will reduce the difference between the simulated environment and the actual environment in which the USV operates, more realistically reflecting the forces and motion of the USV, and better supporting the safety testing system's judgment on whether the USV's current navigation state is safe. Second, the model needs to maintain stable and efficient computational efficiency. The simulation process should not be delayed due to the model's computational efficiency, thus causing the simulation results to be inconsistent with reality and reducing the reliability of the simulation. Third, the model should have an intuitive human-computer interaction parameter adjustment interface, allowing for real-time parameter adjustment for different wave conditions and USV configurations to correspond to the dynamically changing external environment. Fourth, for the hardware-in-the-loop simulation platform, the constructed model should have a certain degree of independence in its deployment method, with clear division of model input and output interfaces to avoid excessive coupling between the model itself and the platform system.

[0023] This invention addresses this situation by proposing a six-degree-of-freedom, lightly coupled dynamic model of an unmanned surface vessel (USV) driven by operational status data from a dual-jet pump. It focuses on accurately simulating the roll and pitch attitudes of the vessel under controlled conditions such as acceleration, constant speed, deceleration, turning, and sharp turns. The model allows for configuration of different dimensions, masses, and wave parameters for the same vessel type via input. Based on Simulink, this invention is implemented through eight modules: a data network transceiver module, a parameter initialization module, a six-dimensional control quantity calculation module, a pose calculation module, a six-dimensional dynamics calculation module, a wave hydrodynamics calculation module, a velocity-roll coupling second-order damping module (u-Roll damping parameter fitting module), and an interactive testing interface. The final result is the following motion characteristics of the dual-jet pump USV:

[0024] The pitch angle increases with speed, reaches a peak after a certain speed and then decreases with increasing speed, eventually becoming slightly smaller than the angle at rest and approaching zero degrees, generally exhibiting a shape similar to a sigma function; Under maximum turning moment input (speed below 30 knots), the stable roll angle is linearly related to the speed, and the roll angle value of the test ship is close to the value of the speed in knots. After connecting to the unmanned surface vessel (USV) safety testing hardware-in-the-loop platform, under the control of a predetermined trajectory and control algorithm, it can achieve trajectory tracking along a specified path in the USV testing interface.

[0025] Furthermore, by configuring parameters and replacing the six-dimensional control input calculation module, dynamic models of unmanned surface vessels with different drive methods of the same ship type can be quickly established.

[0026] The technical solutions provided by the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0027] Figure 1 This is a schematic diagram of a dynamic modeling method for unmanned surface vessel safety testing simulation according to the present invention, which specifically includes the following steps: S101: Obtain the initial simulation parameters for the unmanned surface vessel (USV) safety test simulation and determine the global pose of the USV on the nautical chart; the initial simulation parameters include USV information and wave information.

[0028] S102: Based on the unmanned surface vessel's (USV) propulsion method, acquire the USV's control data, and based on the USV's information and wave information, determine the driving force and torque of the USV in each dimension under the control data.

[0029] S103: Based on wave information and the global pose of the unmanned surface vessel (USV) on the nautical chart, determine the relative wave height of the USV's center point in order to determine the torque of the waves on the USV in each dimension.

[0030] S104: Based on the unmanned surface vessel (USV) information, global pose, driving forces and torques of the USV in various dimensions under the control data, torques of the waves on the USV in various dimensions, and fitting results of the USV's steering and pitch characteristics, a dynamic model is constructed and solved to determine the acceleration, velocity, and position of the USV in various dimensions.

[0031] The steering characteristic fitting result of the unmanned surface vessel is obtained by modeling the second-order model of the roll angle change driven by the roll torque based on the speed-hydrodynamic parameter table and the speed-steering roll angle relationship of the unmanned surface vessel, so as to fit the steering characteristics of the unmanned surface vessel. The pitch characteristic fitting results of the unmanned surface vessel (USV) are obtained by modeling a second-order model of pitch angle change driven by pitch moment based on the USV's speed-hydrodynamic parameter table and speed-pitch angle relationship, in order to fit the USV's pitch characteristics.

[0032] For ease of explanation, the following description focuses solely on the server as the executing entity. The server mentioned in this invention can be a server set up on a business platform, or a device such as a desktop computer or laptop computer capable of executing the solution of this invention.

[0033] Figure 2 This is a schematic diagram of the hardware-in-the-loop simulation platform for security testing in this invention. Figure 2 As can be seen, the main function of this invention is the dynamics simulation module, which contains the eight sub-modules mentioned above. It is the key part that connects the controller hardware and the virtual prototype of the unmanned surface vessel's global motion interaction.

[0034] In one or more embodiments of the present invention, the connection relationships of the various parts within the dynamics simulation module are as follows: Figure 3 As shown, the relationships and data flow between the various modules have been simplified using arrows.

[0035] The data network transceiver module is used to receive external manipulation commands and output six-dimensional attitude calculation information to the human-computer interaction interface.

[0036] The parameter initialization module is used to obtain the initial simulation parameters for the unmanned surface vessel (USV) safety test simulation. The initial simulation parameters include USV information and wave information. Based on this, the USV information and wave information can be initialized and configured. USV information may include initial position, initial attitude, shape, mass and other information; wave information may include speed, amplitude, frequency, wavelength, direction, sea surface resolution and other information.

[0037] The pose calculation module is used to convert the unmanned surface vessel's (USV) body position into a global pose on a nautical chart.

[0038] The six-dimensional control quantity calculation module is used to acquire the control data of the unmanned surface vessel (USV) according to its driving mode, and determine the driving force and torque of the USV in six dimensions under the control data based on the USV's initial attitude, wave information and control data, and then output the calculation results to the dynamics calculation module.

[0039] The wave hydrodynamics calculation module is used to receive information from the unmanned surface vessel (USV) and ocean waves, calculate the simplified torques (X and Y axis forces and yaw moments) of the ocean waves on the USV, and receive the global pose of the USV. It also uses the ocean wave information at the current position of the USV and the preset resolution information of the sea surface to calculate the impact of the waves on the lift and roll angle of the USV.

[0040] The u-Roll damping parameter fitting module is used to fit the actual unmanned surface vessel's steering characteristics (pitch and roll) by combining the speed and hydrodynamic parameter table.

[0041] The six-dimensional dynamics solution module is used to receive the driving force and torque of the unmanned surface vessel (USV) in each dimension under the control data, the torque of the waves on the USV in each dimension, and the fitting results of the USV's steering characteristics, and to perform dynamics solution to determine the motion parameters of the USV, such as acceleration and velocity in each dimension.

[0042] The pose calculation module can further determine the position changes of the unmanned surface vessel (USV) based on its information, global pose, and motion parameters such as acceleration and velocity in various dimensions.

[0043] The interactive testing interface, a UI written in QT, allows users to input wave and control torque data into the constructed dynamic model and displays the output of the unmanned surface vessel's motion status in various dimensions, facilitating direct integration into a safety testing platform for future applications.

[0044] Specifically, in one or more embodiments of the present invention, for the data network transceiver module, the data network transceiver module can receive the control input data (unmanned surface vessel remote controller or QT test program) through UDP / TCP communication, and transmit the pose data to (unmanned surface vessel status monitor or QT test program) for display through the sending end.

[0045] The data network transceiver module may include a UDP receiving module and a UDP sending module, and performs data splitting and merging through Simulink's data package module after receiving and before sending. The UDP communication protocol is as follows: the frequency is 100Hz. Taking the safety test simulation of a dual-jet pump unmanned surface vessel as an example, Table 1 shows the verification protocol and data information contained in the UDP data packet. The first and last four bits are verification information, bits 2 and 3 are timestamps, and bits 4 to 9 represent the six control quantities for the two pumps, rudder direction, and tipping bucket. The tipping bucket is used for the vector movement of the unmanned surface vessel. Bits 10 to 13 represent simplified wave parameter information.

[0046] Table 1 Input Protocol - Network Interface UDP Packet Protocol Communication In addition to the same check bits, the output information also includes 18 state variables, including displacement, velocity, and acceleration in six dimensions, as shown in Table 2. The counterclockwise rotation angle around the axis is defined as positive, and the Z-axis is defined as upward as the positive direction.

[0047] Table 2 Output Protocol - Network Interface UDP Packet Protocol Communication The parameter initialization module initializes the initial state parameters of the unmanned surface vessel (USV), including the x, y, and z coordinates of the USV in the world fixed coordinate system, as well as its attitude parameters: yaw angle (psi), pitch angle (theta), and roll angle (phi). The initial stationary pitch angle (theta) of the USV is 3°. x, y, and z represent the initial position, which is configurable and defaults to (0, 0, 0.5). R_wx_water and R_wy_water represent the multiplication coefficients of water resistance on the USV in different directions, which can be calculated using the uniform vector motion of the USV tested on a still lake surface.

[0048] For the six-dimensional control quantity calculation module, taking the safety test simulation of a dual-jet pump unmanned surface vessel (USV) as an example, the six-dimensional control quantity calculation module can be used to convert the throttle values ​​of the left and right jet pumps into a six-dimensional force acting on the USV for output, serving as the main driving force for the dynamics model. According to the structure of this invention, other types of vessels can be replaced individually here, as long as the output remains consistent.

[0049] Continuing with the example of a dual-pump unmanned surface vessel (USV) safety test simulation, the inputs of the control variables may include the left pump throttle (lf), the right pump throttle (rf), the left pump rudder (ln), the right pump rudder (rn), and the left tipping feed (lk) and the right tipping feed (rk); in addition, the attitude angles of the USV and wave information may also be included; the outputs are the six-dimensional forces and moments, yaw moment (M_rudder), pitch moment (Np), and roll moment (Nr) in the USV's own coordinate system.

[0050] The rudder direction range of the left / right jet pumps is ±30°. The force of the reflected water flow after the tipping bucket is lowered is 30% of the force of the direct water flow. The forces acting on the unmanned surface in the X, Y, and Z axes are calculated using the rudder direction angle, throttle position, and tipping bucket feed rate.

[0051] First, we can establish a coordinate system with the unmanned surface vessel's (USV) forward direction as the positive X-axis, using the right-hand rule. That is, the positive Y-axis is perpendicular to the X-axis and points to the left of the USV, and the positive Z-axis is vertically upward. The rotation direction is defined as the angle of clockwise rotation around the relevant X, Y, and Z coordinate axes.

[0052] When the rudder direction of the left injection pump is 0, the thrust in the X-axis direction generated by the throttle of the left injection pump can be determined by the following formula: Fxl = LF·((0.65·lk) + 350) / 1000 When the rudder direction of the right injection pump is 0, the thrust in the X-axis direction generated by the throttle of the right injection pump can be determined by the following formula: Fxr = RF·((0.65·rk) + 350) / 1000 In the formula, Fxl is the X-axis thrust generated by the left injection pump throttle, LF is the maximum thrust that the left injection pump can output, lk is the left tipping bucket feed amount, Fxr is the X-axis thrust generated by the right injection pump throttle, RF is the maximum thrust that the right injection pump can output, and rk is the right tipping bucket feed amount. Taking the right tipping bucket as an example, when the right tipping bucket is fully tilted down, the direction of Fxr becomes the negative maximum value, which is 30% of the maximum thrust. At this time, there is no Y-axis component force of a single injection pump.

[0053] When the rudder direction of the left injection pump changes, the X-axis thrust and Y-axis thrust generated by the throttle of the left injection pump are determined by the following formula: Ftl = LF·(lk+1000) / 2000; Freverse_l= LF·0.3·(1000-lk) / 2000 Fxl = cos(lj)·(Ftl - Freverse_l); Fyl = sin(lj)·(Ftl + Freverse_l) When the rudder direction of the right injection pump changes, the X-axis thrust and Y-axis thrust generated by the throttle of the right injection pump are determined by the following formula: Ftr = RF·(rk+1000) / 2000; Freverse_r = RF·0.3·(1000-rk) / 2000 Fxr = cos(rj)·(Ftr - Freverse_r); Fyr = sin(rj)·(Ftr + Freverse_r) In the formula, Ftl represents the corresponding thrust output by the left jet pump under the control of the left tipping bucket feed, Freverse_l represents the reaction thrust generated by the left tipping bucket, lj represents the yaw angle of the left tipping bucket, Ftr represents the corresponding thrust output by the right jet pump under the control of the right tipping bucket feed, Freverse_r represents the reaction thrust generated by the right tipping bucket, and rj represents the yaw angle of the right tipping bucket. The reaction thrust generated by the tipping bucket represents the resistance of the jet pump tipping bucket. The tipping bucket is used to reflect the jet pump jet, giving the ship a force opposite to the direction of the jet.

[0054] At this point, the jet pumps exert forces along both the X and Y axes. Based on the thrust generated by the left and right jet pump throttles in each direction, the resultant force of the unmanned surface vessel in each direction is determined using the following formula:

[0055] F_x = (Fxr + Fxl)·cos(pitch); F_y = (Fyr + Fyl)·cos(roll) F_z = (Fxr + Fxl)·sin(pitch)·cos(roll) - (Fyr + Fyl)·sin(roll) Therefore, the pitching moment of the unmanned surface vessel can be calculated as follows, where the moment coefficient of 0.125 can be estimated and modified according to different unmanned surface vessel types.

[0056] Np = - sign(pitch)·Z·cos(pitch)·ship_l / 8 The calculation of roll and yaw moments is divided into two models: vector and normal operation. In vector mode, the ship is assumed to be unaffected by yaw moment. The prerequisites for determining the vector model are: 1. Both the port and starboard jet pump rudder directions are not zero; 2. The thrust directions of the port and starboard jet pumps in the X-axis direction are opposite. Otherwise, it is in normal mode. When operating in normal mode, the yaw moment can be calculated based on either the difference in thrust between the port and starboard sides or the same-direction component.

[0057] if ln == 0 &&rn == 0 M_rudder = (Fxl - Fxr)·ship_w / 2; else M_rudder = (Fyr + Fyl)·ship_l / 2; end The magnitude of the rolling moment is: Nr = (Fyr + Fyl)·0.5.

[0058] In the formula, F_x is the resultant force of the unmanned surface vessel (USV) in the X-axis direction, F_y is the resultant force of the USV in the Y-axis direction, F_z is the resultant force of the USV in the Z-axis direction, pitch is the pitch angle of the USV, roll is the roll angle of the USV, Fyr is the thrust in the Y-axis direction generated by the right jet pump throttle, Fyl is the thrust in the Y-axis direction generated by the left jet pump throttle, Np is the pitch moment of the USV, sign() represents the sign function, ship_l is the length of the USV, M_rudder is the rotational torque generated by the dual jet pumps on the USV, ship_w is the width of the USV, Nr is the roll moment of the USV, and ship_h is the height of the USV (height from the deck to the ground).

[0059] For the wave hydrodynamic calculation module, the wave hydrodynamic calculation module may include a wave distribution model and a hydrodynamic parameter table. The hydrodynamic parameter table can be obtained through the following process: within the throttle range of the unmanned surface vessel (USV), for each preset throttle, the speed of the USV when it accelerates to uniform linear motion under the corresponding thrust at that throttle in still water is obtained; thus, based on the relationship between the corresponding thrust at each throttle and the speed of the USV when it accelerates to uniform linear motion, a velocity hydrodynamic parameter table of the USV is established.

[0060] That is, the speed hydrodynamic parameter table is obtained by measuring and collecting data on the surface of lakes and other still waters by unmanned surface vessels. A specific throttle is given to the unmanned surface vessel, and the corresponding thrust is calculated. When the vessel accelerates to a certain speed, it tends to move in uniform linear motion (forward or backward or left and right lateral linear motion). At this time, it is assumed that the calculated thrust of the unmanned surface vessel is the same as the water resistance. During the modeling process, this thrust and speed are plotted to obtain the hydrodynamic parameter table.

[0061] The wave distribution model can receive wave amplitude A, velocity wave_vel, global angle wave_theta, and frequency wave_w from the parameter initialization module, as well as the current position of the unmanned surface vessel (USV) output from the pose calculation module. It then calculates the relative wave height at the USV's center point and outputs this to the dynamics calculation module to calculate the lift, pitch, and roll torque of the USV under the influence of the waves. For simplicity, the input wave has only one main sine function component; in complex cases, n sets of sine components can be superimposed. The relative wave height at the USV's center point is calculated using the input USV's current position, time, and wave information, as shown in the following formula:

[0062] h(xyt) = Asin(wave_w / wave_vel)[(xcosθ + ysinθ) - wave_w·t + wave_theta] In the formula, x is the X-axis coordinate of the global pose of the unmanned surface vessel on the nautical chart, y is the Y-axis coordinate of the global pose of the unmanned surface vessel on the nautical chart, θ is the global angle of the wave direction (the angle with the X-axis), t is time, and wave_theta is the initial phase angle of the wave.

[0063] To simplify the model, it is assumed that waves provide three torque inputs for the unmanned surface vessel (USV): heave torque, roll torque, and pitch torque. The sea surface projection of the USV is meshed, with the mesh resolution manually configured in the parameter initialization module. The three torque calculation methods are shown in the following code:

[0064] for j = ceil(-w_ / 2): floor(w_ / 2) for i = ceil(-l_ / 2): floor(l_ / 2) if i == 0 || j == 0 continue else x_b = i×res; y_b = -j×res; x_Fix = Rotate_s2g(1,1:2)×[x_b; y_b] + x_c; y_Fix = Rotate_s2g(2,1:2)×[x_b; y_b] + y_c; end h_ijt_d = wave_model(x_Fix, y_Fix, t, Wave_vel, wave_theta, A, wave_w); H_a = H_a + h_ijt_d; H_p = H_p + h_ijt_d×sign(i); H_r = H_r + h_ijt_d×sign(j); end end The projection area of ​​the unmanned surface vessel on the sea surface is designed according to the resolution and divided into square regions w and l, where l is the number of squares on the long side and w is the number of squares on the wide side. Then, the torques H_a, H_p, and H_r of the water on the unmanned surface vessel's buoyancy, roll, and pitch are statistically analyzed for each region l and w. If any index is 0 during iteration, it represents a boundary point and is not calculated; the process then proceeds to the next calculation loop. If there is no index 0, the coordinates of the current indexed square block (x_b, y_b) are transformed to the global coordinate system (x_Fix, y_Fix) using a coordinate transformation matrix. Rotat_s2g is the coordinate transformation matrix from the UAV to the global coordinate system, and (x_c, y_c) are the global coordinates of the UAV's center. Then, the water level in the current positive direction region is calculated using the wave_model function, h(xyt), to determine the torques of the waves in this grid region on the UAV's buoyancy, roll, and pitch: H_a, H_p, H_r. The buoyancy, roll, and pitch torques H_a, H_p, and H_r are then accumulated. sign is a sign function used to determine whether the location is left-right or forward-backward based on the positive or negative sign of the i and j loops, and is used to control the direction of the accumulated torque.

[0065] To determine the moments of the waves on the unmanned surface vessel (USV) in various dimensions, the area of ​​the USV's sea surface projection can be first divided into grids. For each grid area, its global position on the nautical chart can be determined. Then, based on the wave's speed, amplitude, global angle, and frequency, as well as the grid area's global position on the nautical chart, the water level of that grid area can be determined. Next, based on the water level of that grid area, the moments of the waves on the USV's buoyancy, roll, and pitch can be determined. Finally, the moments of the waves on the USV's buoyancy, roll, and pitch in each grid area can be summed to obtain the moments of the waves on the USV in various dimensions.

[0066] For the velocity-roll coupling second-order damping module, or the u-Roll damping parameter fitting module, the steady-state velocity values ​​in the forward direction after a full rudder turn at different velocities can be obtained from the unmanned surface vessel's (USV) velocity-hydrodynamic parameter table. Then, based on the steady-state velocity values ​​in the forward direction after a full rudder turn at different velocities and the velocity-turning roll angle relationship of the USV, a second-order model of roll angle variation driven by roll moment is established. The first damping parameter in the second-order roll angle variation model is then calibrated using the final value theorem of the Laplace transform of the second-order system, obtaining the correspondence between the USV's forward velocity and the first damping parameter, which serves as the fitting result for the USV's steering characteristics. It can be understood that the USV's steering characteristics can be pre-fitted here.

[0067] For example, for a single-unit dual-jet pump unmanned surface vessel (USV), based on experimental testing experience, the roll angle of this USV is approximately linearly related to its speed (represented by knots) during turning, with a scaling factor close to 1. That is, when the forward speed is 10 knots, the roll angle of the USV during turning is 10 degrees; however, overshoot exists. The difficulty in simulating this process lies in the loss of driving force during turning. During this process, the forward speed is affected, resulting in a decrease in speed. Therefore, speed and roll angle cannot be directly correlated. It is necessary to first clarify the impact of the turning process on the speed and calculate the final speed after the turn stabilizes.

[0068] In one or more embodiments of the present invention, a second-order model of roll angle change driven by roll moment is proposed to address this key characteristic. The final value theorem of the Laplace transform of the second-order system and the velocity-hydrodynamic parameter table are used to fit and simulate the steering characteristics of the unmanned surface vessel. The damping of the second-order system is set to match the roll angle change corresponding to the final value of the velocity under the influence of steering.

[0069] By using the velocity-hydrodynamic parameter module and the prior velocity-steering roll angle relationship, a second-order model of roll angle variation driven by roll moment is constructed. The second-order model of roll angle variation driven by roll moment is as follows: F_r = Nr + H_r · S_w / (10·sigma+1) - R_resistance_r - roll_phi In the formula, F_r is the roll moment of the unmanned surface vessel (USV), Nr is the roll moment of the dual-jet pump, H_r is the roll moment of the water body on the USV, sigma is the first damping parameter, which is given by the correspondence between the forward velocity of the USV and the first damping parameter (|u|-sigma table), R_resistance_r is the roll velocity term, roll_phi is the roll angle term, and S_w is the seawater density coefficient set according to the experimental water environment.

[0070] The final value theorem is used to calibrate the system parameter sigma in the second-order model by understanding the characteristics of roll angle change during turning at corresponding speeds. The specific steps are as follows:

[0071] 1) Establish a speed hydrodynamic parameter table and import it into the corresponding module to drive the dynamic model of the unmanned surface vessel. At this time, after the unmanned surface vessel inputs the throttle, it can achieve the corresponding acceleration, deceleration and uniform motion according to the corresponding hydrodynamic parameters. 2) Clarify the speed-roll angle relationship during the turning process of your unmanned surface vessel. For example, if the relationship between the speed u (knots) of an unmanned surface vessel in the X-axis direction and the roll angle is linear and the scaling factor is close to 1, that is, when the speed is 10 knots, the roll angle of the unmanned surface vessel during the turn is 10 degrees. 3) As the angle of the jet pump changes during the turning process, the force on the unmanned surface vessel changes, which causes the speed of the ship in the X-axis direction to change. Therefore, before the speed of the ship in the X-axis direction stabilizes, the roll angle of the unmanned surface vessel undergoes a change process. At this time, it is necessary to collect the steady-state speed values ​​of the unmanned surface vessel after turning at different speeds according to the hydrodynamic-speed parameter table module. 4) The input of steering control can be mapped from the steady-state speed value to the steady-state roll angle value. At this time, according to the second-order model of the roll angle, the sigma parameter in F_r is calibrated using the final value theorem.

[0072] 5) Finally, the |u|-sigma relationship curve is obtained.

[0073] The damping mapping relationship of the second-order velocity-roll model obtained using the above method is as follows: Figure 4 As shown, the horizontal axis represents velocity (unit: m / s), and the vertical axis represents the sigma value.

[0074] Similarly, in one or more embodiments of the present invention, when obtaining the fitting results of the unmanned surface vessel's (USV) steering characteristics, the steady-state values ​​of the forward velocity after full rudder steering at different forward velocities can be obtained first from the USV's velocity-hydrodynamic parameter table. Then, based on the steady-state values ​​of the forward velocity after full rudder steering at different forward velocities and the USV's velocity-pitch angle relationship, a second-order model of pitch angle variation driven by pitch moment is established. Finally, the second damping parameter in the second-order model of roll angle variation is calibrated using the final value theorem of the Laplace transform of the second-order system, obtaining the correspondence between the USV's forward velocity and the second damping parameter, which serves as the fitting result of the USV's pitch characteristics. It can be understood that the USV's pitch characteristics can be pre-fitted here.

[0075] The speed-pitch angle relationship of the unmanned surface vessel (USV) refers to the following: When the USV is traveling, if its speed is below the first speed in the forward direction, the pitch angle of the USV increases as the speed increases. This is the first stage. After the speed in the forward direction reaches the first speed, the USV enters the second stage. At this time, the pitch angle of the USV begins to decrease and stabilizes in the third stage when the speed in the forward direction continues to increase. The pitch angle is close to the 0-3 degree range, and the USV skips across the water.

[0076] Based on the three-stage characteristics, a pitch angle change model can be modeled under the pitch moment driven by the unmanned surface vessel's gravity and the driving force of ocean waves, and the pitch characteristics of the unmanned surface vessel can be fitted to determine the fitting result of the pitch characteristics of the unmanned surface vessel.

[0077] Specifically, during navigation, the pitch angle of a single unmanned surface vessel (USV) changes in three stages as its speed increases, as described above. For example, in one or more embodiments of this invention, the USV's pitch angle in a stationary state is 3°. During the speed range of 0-11 knots, the pitch angle gradually increases from 3° to 13°. Then, as the speed increases further, during the speed range of 11-20 knots, the pitch angle monotonically decreases, gradually returning from 13° to 3°. In the final stage, during the speed range of 20-35 knots, the pitch angle changes slowly, varying between 3° and 0°, and the vessel exhibits characteristics of skimming across the water. The difficulty in simulating this process lies in the fact that the USV's pitch angle change is influenced by multiple factors, including its own gravity, speed, and jet thrust vectoring. A simple second-order system oscillation or convergence process cannot satisfy the dynamic process of these three stages.

[0078] In one or more embodiments of the present invention, based on a hydrodynamic parameter table, a special second-order system model with a speed-pitch moment control term is proposed to fit and simulate the speed-pitch characteristics of the unmanned surface vessel, and to configure the parameters of the speed-pitch moment control term and the second-order system parameters to match the pitch angle change of the unmanned surface vessel during the speed change process.

[0079] By combining the velocity-pitch angle relationship with the velocity-hydrodynamic parameter module, a second-order model driven by pitch moment is modeled in conjunction with the velocity-pitch moment control term. The second-order model driven by pitch moment in conjunction with the velocity-pitch moment control term is as follows: F_p = Np +· H_p · S_w / (sqrt(u^2 +v^2)+2) + L_p + fp_1 + fp_2 In the formula, F_p is the pitching moment of the unmanned surface vessel, N_p is the resultant pitching moment generated by the dual jet pumps, H_p is the pitching moment of the unmanned surface vessel caused by the waves, fp_1 is the pitching angle term, fp_2 is the pitching angular velocity term, L_p is the velocity term in the X-axis direction, which includes the velocity-pitch control term l_w.

[0080] l_w = 0.25 · ship_l · (1 / (1+exp(abs(u)-6))) L_p = sign(u) · l_w · L_w By setting a threshold for the monotonic change of velocity-pitch angle in the second stage (this parameter is 6 for the unmanned surface vessel in this invention), the characteristics of the unmanned surface vessel in the three stages of velocity-pitch angle are modeled. Then, using the final value theorem to realize the pitch angle change characteristics at the corresponding velocity, the parameters of the system terms fp_1 and fp_2 in the second-order model are calibrated. The specific steps are as follows:

[0081] 1) Establish a speed hydrodynamic parameter table and import it into the corresponding module to drive the dynamic model of the unmanned surface vessel. At this time, after the unmanned surface vessel inputs the throttle, it can achieve the corresponding acceleration, deceleration and uniform motion according to the corresponding hydrodynamic parameters. 2) Determine the key thresholds for the three stages of pitch angle change of the unmanned surface vessel (USV): the initial angle, the peak angle, and the pitch angle during high-speed water drift. In this embodiment, the USV's pitch angles are 3°, 13°, and 1.5°, along with the corresponding speeds of 0 knots, 12 knots, and greater than 30 knots.

[0082] 3) Based on the quantitative relationship between peak velocity and pitch angle (13° and 12 knots in this embodiment), set the speed threshold term in the speed-pitch moment control term l_w (6 m / s, approximately 12 knots in this embodiment). Then, the throttle control input can determine the speed of the unmanned surface vessel through the speed hydrodynamic parameter table, thereby fixing the first three terms of F_p. Then, based on the speed difference of control term l_w at different speeds and the final value of the pitch angle velocity limit (1.5° in this embodiment), use the final value theorem to determine the parameters of fp_1 and fp_2 terms (i.e., the natural frequency and damping ratio of the second-order system) at different speeds. 4) Finally, a second-order system model based on the velocity-pitch angle control term is obtained.

[0083] The six-dimensional dynamics solution module is the core component of the overall operation. It constructs a dynamic model by receiving multiple inputs (driving forces and torques in various dimensions of the unmanned surface vessel under the control data, torques of the waves on the unmanned surface vessel in various dimensions, and fitting results of the unmanned surface vessel's steering characteristics), solves the overall dynamics of the unmanned surface vessel, and outputs the acceleration, velocity, and position information of the six degrees of freedom.

[0084] 1) Force in the X-axis direction: u_dot = (F_x -(M+X_vr)·v·r + X_current) / M Where u_dot is the acceleration of the unmanned surface vessel (USV) in the X-axis direction, F_x is the total thrust generated by the dual-jet pump in the X-axis direction, M is the mass of the USV, X_vr is the velocity coupling damping coefficient, X_vr = 5.33·M, v is the velocity of the USV in the Y-axis direction, r is the yaw rotation speed of the USV, and X_current is the force of the waves in the X-axis direction.

[0085] 2) Force in the Y-axis direction: v_dot = (F_y + Y_current - 0.15·(M + Y_ur )·u·r) / M Where v_dot is the acceleration of the unmanned surface vessel in the Y-axis direction, F_y is the resultant force of the dual-jet pump in the Y-axis direction, Y_current is the velocity coupling damping coefficient, Y_ur = 0.36·M, Y_ur is the velocity coupling damping coefficient in the Y-axis direction, set to 0.36M, and u is the velocity of the unmanned surface vessel in the X-axis direction.

[0086] 3) Force in the Z-axis direction: F_h = F_z + H_a · S_w / (sqrt(u^2 +v^2)+2) - R_resistance_h - W_s ·9.8 · min(d_ship_z, 0) - M · 9.8 + L_w Where F_h is the lift force of the unmanned surface vessel in the Z-axis direction, F_z is the resultant lift force generated by the dual jet pumps in the Z-axis direction, S_w is the density of seawater, R_resistance_h is the damping force related to the lift velocity, W_s = -M / ship_z_balance, M is the mass of the unmanned surface vessel, ship_z_balance is the distance between the bottom of the unmanned surface vessel and the horizontal plane when it is stationary on the water surface, d_ship_z is the difference between the initial depth and the current depth of the vessel, and L_w is the dynamic lift force.

[0087] The forces along the Z-axis include the Z-axis component of the jet pump thrust, the wave lift (the second term), the damping force R_resistance_h related to the ascent speed, buoyancy, gravity, and dynamic lift L_w. If d_ship_z is negative, it indicates the ship is moving at high speed on the sea surface in a skipping motion, where there is no buoyancy. L_w gradually increases with speed, reaching its upper limit after a certain speed, simulating the height increase of the unmanned surface vessel after acceleration.

[0088] W_s = -M / ship_z_balance R_resistance_h = M·w L_w = min(sqrt((u^2 + v^2) / 75),1) · 0.6 · M · 9.8 The motion under force in the Z-axis direction can be approximated as oscillating motion. Without considering the additional heave effect of the waves, L_w realizes the switching of dynamic lift during the high-speed and low-speed operation of the ship. When a certain speed is reached, the unmanned surface vessel is at the critical value of dynamic lift.

[0089] 4) Yaw resultant moment N: N = M_rudder - M_resist Where M_rudder is the rotational torque generated by the jet pump on the unmanned surface vessel, and M_resist is the damping force M_resist of the rotational speed. That is, the resultant torque of yaw is simplified to the rotational torque generated by the jet pump and the damping force of the rotational speed.

[0090] 5) Pitch moment F_p: F_p = Np +· H_p · S_w / (sqrt(u^2 +v^2)+2) + L_p + fp_1 + fp_2 Where F_p is the pitching moment of the unmanned surface vessel, N_p is the resultant pitching moment generated by the dual jet pumps, H_p is the pitching moment generated by the water body in the aforementioned code, L_p is the velocity term in the X-axis direction, fp_1 is the pitching angle term, and fp_2 is the pitching angular velocity term.

[0091] fp_1 and fp_2 constitute a second-order model of the pitch angle, as follows: fp_1 = -5 · I_p · (theta - 0.05236) fp_2 = -1.66 · I_p · q This represents the elastic force of the water (angle-related variable fp_1, theta being the pitch angle) and the damping force on the pitch angular velocity (angular velocity-related quantity fp_2, q being the pitch angular velocity) under static conditions at an equilibrium position of 3° (the pitch angle of the unmanned surface vessel). The hydrodynamic force L_p changes with speed, reflecting the change in the pitch angle input during the unmanned surface vessel's speed changes. By varying the lever arm of the pitch moment acting on the bottom of the unmanned surface vessel at different speeds, a variation curve consistent with actual navigation tests is achieved for the unmanned surface vessel at different speeds. At speeds around 10⁻¹² (5 m / s), the lever arm of the moment changes significantly and gradually approaches zero.

[0092] l_w = 0.25 · ship_l · (1 / (1+exp(abs(u)-6))) L_p = sign(u) · l_w · L_w Where, l_w is the first formula above, used to control the effect of pitch torque reduction after the speed reaches a certain limit, exp is the exponential function of e, abs is the absolute value function, L_w is min(sqrt((u^2 + v^2) / 75),1) * 0.6 *M * 9.8, which represents the torque caused by gravity after the unmanned surface vessel pitches after exceeding a certain speed, min() means taking the minimum value, and sqrt means square root operation.

[0093] Ultimately, the relationship between the achieved speed and pitch angle is as follows: Figure 5 As shown, Figure 5 This is a schematic diagram of a u-pitch curve in this invention.

[0094] 6) Rolling torque F_r The roll moment is defined as follows: F_r = Nr + H_r · S_w / (10·sigma+1) - R_resistance_r - roll_phi In the formula, F_r is the roll moment acting on the unmanned surface vessel, Nr is the resultant roll moment caused by the dual-jet pumps, H_r is the aforementioned roll moment of the water body on the vessel, sigma is an adjustment parameter given by the |u|-sigma table, R_resistance_r is the roll speed term, and roll_phi is the roll angle term. It is expressed as follows:

[0095] roll_phi = sigma·I_r·phi R_resistance_r = K_r · I_r · p Where phi represents the roll angle, p represents the roll angular velocity, and I_r is the moment of inertia in the roll direction. As a second-order system, since the final value of phi differs under different input torques, the system is considered a variable-damping system, and adjustments are made by regulating sigma and K_r respectively. The K_r value and sigma work together on the normalized second-order model transfer function. sigma controls the final value to ensure accurate roll angle, while K_r controls the overshoot (the overshoot of the roll angle change after a step signal of ln, rn in the steering input). It is assigned a value through the steering switching mode. In this invention, two K_r values ​​are set: 3.0 and 0.5. When the steering process is in a straight or same-direction steering, it is set to 3.0 to maintain normal overshoot, and when the steering direction is opposite to the current direction, it is set to 0.5 to reduce roll angle overshoot.

[0096] Then, based on the roll angle changes under different steering switching states, the K_r value is adjusted to realize the change of second-order system overshoot under different speeds and modes, so as to simulate the large roll angle at the moment of high-speed turning.

[0097] For the pose calculation module, the pose calculation module can receive the X-axis velocity u, Y-axis velocity v, and yaw angle psi from the unmanned surface vessel dynamics calculation module as inputs. These are all variables in the unmanned surface vessel's body coordinate system. After matrix rotation transformation, they are transformed into the X and Y axis velocity values ​​of the unmanned surface vessel in the global coordinate system.

[0098] For the interactive testing interface, a software interface for model testing was developed using QT. This interface allows for the configuration of dynamic model parameters and network ports, and also displays the unmanned surface vessel's operating status and pose parameters, such as... Figure 6 As shown, Figure 6 This is a schematic diagram of a UI interface in this invention.

[0099] The system displays xy-plane coordinates, u-direction velocity, yaw rate, altitude, yaw angle, pitch angle, and roll angle by inputting six control variables.

[0100] based on Figure 1The present invention describes a dynamic modeling method for unmanned surface vessel (USV) safety testing simulation. This method simplifies the USV dynamic model and, addressing the specific requirements of roll and pitch dynamic responses, proposes a second-order model for roll angle variation driven by roll moment, combining speed-hydrodynamic parameter tables and speed-turning roll angle relationships. It also proposes a second-order model for pitch angle variation driven by pitch moment, combining speed-hydrodynamic parameter tables and speed-pitch angle relationships. Utilizing readily available data on the actual USV's thrust-speed, forward direction speed-turning roll angle relationships during turning, and speed-pitch angle relationships, the method can accurately and quickly fit and establish the USV's roll and pitch dynamic response relationships, creating a complete USV dynamic model. This simplifies and decouples the USV dynamic modeling process, improving the calculation speed and simulation fitting accuracy of the USV dynamic model.

[0101] To address the safety requirements of intelligent control systems for unmanned surface vessels (USVs) regarding dynamic model characteristics (roll, pitch, and trajectory tracking), this study utilizes the decomposition principle combined with a Simulink model to break down the dynamic model into multiple functional modules. Multiple secondary system models are used to decouple and simplify the originally complex and poorly adaptable USV dynamic model. Simulation characteristics of the experimental USV are achieved through a hydrodynamic solution module and a velocity-roll coupling second-order damping module.

[0102] This invention presents a dynamic model of a single-unit dual-jet pump unmanned surface vessel (USV) and integrates it with a hardware-in-the-loop (BIL) test platform for the safety testing of the USV's intelligent control system. This model achieves near-real-vessel dynamic characteristics, including pitch angle simulation, roll angle simulation, parameter configuration, and automated parameter fitting. While modifications to the USV's dimensions and mass can alter the model, this significantly reduces the cost of testing the USV's intelligent control system algorithm, lowers the risks of testing in complex sea conditions, and improves the efficiency of safety testing for the USV's intelligent control system. This provides strong support for the development and testing of USV intelligent control algorithms.

[0103] When applying the dynamic modeling method for unmanned surface vessel safety testing simulation provided by this invention, it is not necessary to base it on... Figure 1 The steps shown are executed in sequence. The specific execution order of each step can be determined as needed, and this invention does not impose any restrictions on it.

[0104] The above describes a dynamic modeling method for unmanned surface vessel (USV) safety testing simulation provided by one or more embodiments of the present invention. Based on the same idea, the present invention also provides a corresponding dynamic modeling device for USV safety testing simulation, such as... Figure 7 As shown.

[0105] Figure 7A schematic diagram of a dynamic modeling device for unmanned surface vessel safety testing simulation provided by the present invention includes: The acquisition module 201 is used to acquire the initial simulation parameters for the unmanned surface vessel (USV) safety test simulation and determine the global pose of the USV on the nautical chart; the initial simulation parameters include USV information and wave information. The control module 202 is used to acquire the control data of the unmanned surface vessel (USV) according to the driving mode of the USV, and to determine the driving force and torque of the USV in each dimension under the control data based on the USV information and wave information. The wave impact module 203 is used to determine the relative wave height of the center point of the unmanned surface vessel (USV) based on wave information and the global pose of the USV on the nautical chart, so as to determine the torque of the waves on the USV in various dimensions. The dynamics solution module 204 is used to construct a dynamic model based on the unmanned surface vessel (USV) information, global pose, driving force and torque of the USV in various dimensions under the control data, torque of the waves on the USV in various dimensions, and fitting results of the USV's steering characteristics and pitch characteristics to determine the acceleration, velocity and position of the USV in various dimensions. Specifically, the steering characteristic fitting result of the unmanned surface vessel (USV) is obtained by modeling a second-order model of roll angle change driven by roll moment based on the USV's speed-hydrodynamic parameter table and speed-steering roll angle relationship, in order to fit the USV's steering characteristics; the pitch characteristic fitting result of the USV is obtained by modeling a second-order model of pitch angle change driven by pitch moment based on the USV's speed-hydrodynamic parameter table and speed-pitch angle relationship, in order to fit the USV's pitch characteristics.

[0106] The present invention also provides a computer-readable storage medium storing a computer program that can be used to execute the above-described... Figure 1 The provided method for modeling dynamic models for unmanned surface vessel safety testing and simulation.

[0107] The present invention also provides Figure 8 The schematic diagram of the computer device shown is as follows: Figure 8 As shown, at the hardware level, this computer device includes a processor, internal bus, network interface, memory, and non-volatile memory, and may also include other hardware required for business operations. The processor reads the corresponding computer program from the non-volatile memory into memory and then executes it to achieve the above. Figure 1 The provided method for modeling dynamic models for unmanned surface vessel safety testing and simulation.

[0108] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the methods described above. Any references to memory, storage, databases, or other media used in the embodiments provided by this invention can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, or optical storage, etc. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0109] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this invention.

Claims

1. A method for modeling a dynamic model for unmanned surface vehicle safety testing simulation, characterized in that, The application relates to a method for simulating the safety of an unmanned ship. The method comprises the following steps: acquiring initial simulation parameters of an unmanned ship safety test simulation, and determining the global position of the unmanned ship on a sea chart; the initial simulation parameters comprise unmanned ship information and sea wave information; according to the driving mode of the unmanned ship, acquiring control data of the unmanned ship, and determining the driving force and torque of the unmanned ship in each dimension under the control data driving according to the unmanned ship information and the sea wave information; according to the sea wave information and the global position of the unmanned ship on the sea chart, determining the relative wave height of the center point of the unmanned ship to determine the torque of the sea wave on the unmanned ship in each dimension; according to the unmanned ship information, the global position, the driving force and torque of the unmanned ship in each dimension under the control data driving, the torque of the sea wave on the unmanned ship in each dimension, and the turning characteristic fitting result and the pitching characteristic fitting result of the unmanned ship, a dynamic model is constructed to determine the acceleration, speed and position of the unmanned ship in each dimension; 2. The method of claim 1, wherein, wherein the turning characteristic fitting result is modeled according to the speed hydrodynamic parameter table of the unmanned ship and the speed-turning roll angle relationship to the roll torque driving roll angle change second-order model to fit the turning characteristic of the unmanned ship; and the pitching characteristic fitting result is modeled according to the speed hydrodynamic parameter table of the unmanned ship and the speed-pitching angle relationship to the pitching torque driving pitching angle change second-order model to fit the pitching characteristic of the unmanned ship. The unmanned ship information comprises the initial position, initial attitude, shape and mass of the unmanned ship.

3. The method of claim 1, wherein, The sea wave information comprises the speed, amplitude, frequency, wavelength and direction of the sea wave. The unmanned ship is a double-jet-pump single unmanned ship; the control data comprises the left jet-pump throttle, the right jet-pump throttle, the left jet-pump rudder direction, the right jet-pump rudder direction, the left hopper feeding amount and the right hopper feeding amount; According to the unmanned ship information and the sea wave information, the driving force and torque of the unmanned ship in each dimension under the control data driving are determined, specifically comprising: taking the forward direction of the unmanned ship as the positive direction of the X axis, and establishing a coordinate system according to the right-hand rule; when the left jet-pump rudder direction is 0, the X-axis direction thrust generated by the left jet-pump throttle is determined by the following formula: Fxl = LF·((0.65·lk) + 350) / 1000; when the right jet-pump rudder direction is 0, the X-axis direction thrust generated by the right jet-pump throttle is determined by the following formula: Fxr = RF·((0.65·rk) + 350) / 1000; when the left jet-pump rudder direction changes, the X-axis direction thrust and the Y-axis direction thrust generated by the left jet-pump throttle are determined by the following formula: Ftl = LF·(lk+1000) / 2000; Freverse_l= LF·0.3·(1000-lk) / 2000; Fxl = cos(lj)·(Ftl - Freverse_l); Fyl = sin(lj)·(Ftl + Freverse_l); when the right jet-pump rudder direction changes, the X-axis direction thrust and the Y-axis direction thrust generated by the right jet-pump throttle are determined by the following formula: Ftr = RF · (rk + 1000) / 2000; Freverse_r = RF · 0.3 · (1000 - rk) / 2000; Fxr = cos(rj) · (Ftr - Freverse_r); Fyr = sin(rj) · (Ftr + Freverse_r); According to the thrusts in each direction generated by the left and right jet pumps, the resultant forces of the unmanned ship in each direction are determined by the following formula: F_x = (Fxr + Fxl) · cos(pitch); F_y = (Fyr + Fyl) · cos(roll); F_z = (Fxr + Fxl) · sin(pitch) · cos(roll) - (Fyr + Fyl) · sin(roll); The pitch moment of the unmanned ship is determined by the following formula: Np = - sign(pitch) · Z · cos(pitch) · ship_l / 8; If the rudder directions of the left and right jet pumps are both not 0 and the X-axis direction thrusts generated by the left and right jet pumps are opposite, then the yaw moment of the unmanned ship is determined by the following formula: M_rudder = (Fyr + Fyl) · ship_l / 2; otherwise, the yaw moment of the unmanned ship is determined by the following formula: M_rudder = (Fxl - Fxr) · ship_w / 2; The roll moment of the unmanned ship is determined by the following formula: Nr = (Fyr + Fyl) · 0.5 · ship_h; Wherein, Fxl is the X-axis direction thrust generated by the left jet pump, LF is the maximum thrust that the left jet pump can output, lk is the left bucket feeding amount, Fxr is the X-axis direction thrust generated by the right jet pump, RF is the maximum thrust that the right jet pump can output, rk is the right bucket feeding amount, Ftl is the corresponding thrust output by the left jet pump under the control of the left bucket feeding amount, Freverse_l is the counter thrust generated by the left bucket, lj is the rudder yaw angle of the left bucket, Ftr is the corresponding thrust output by the right jet pump under the control of the right bucket feeding amount, Freverse_r is the counter thrust generated by the right bucket, rj is the rudder yaw angle of the right bucket, pitch is the pitch angle of the unmanned ship, roll is the roll angle of the unmanned ship, Fyr is the Y-axis direction thrust generated by the right jet pump, Fyl is the Y-axis direction thrust generated by the left jet pump, F_x is the resultant force of the unmanned ship in the X-axis direction, F_y is the resultant force of the unmanned ship in the Y-axis direction, F_z is the resultant force of the unmanned ship in the Z-axis direction, Np is the pitch moment of the unmanned ship, sign() represents the sign function, ship_l is the length of the unmanned ship, M_rudder is the rotation moment generated by the double jet pumps on the unmanned ship, ship_w is the width of the unmanned ship, Nr is the roll moment of the unmanned ship, and ship_h is the height of the unmanned ship.

4. The method of claim 1, wherein, The relative wave height of the center point of the unmanned ship is determined according to the sea wave information and the global pose of the unmanned ship on the sea chart, and specifically includes: According to the speed, amplitude, global angle and frequency of the sea wave, and the global position of the unmanned ship on the sea chart, the relative wave height of the center point of the unmanned ship is determined by the following formula: h(xyt) = Asin(wave_w / wave_vel)[(xcosθ + ysinθ) - wave_w·t + wave_theta]; Wherein, h(xyt) is the relative wave height of the center point of the unmanned ship, A is the amplitude of the sea wave, wave_w is the frequency of the sea wave, wave_vel is the speed of the sea wave, x is the X-axis coordinate of the global position of the unmanned ship on the sea chart, y is the Y-axis coordinate of the global position of the unmanned ship on the sea chart, θ is the global angle of the sea wave direction, t is the time, and wave_theta is the initial phase angle of the sea wave.

5. The method of claim 1, wherein, The determination of the moment of the sea wave on each dimension of the unmanned ship specifically includes: The region occupied by the unmanned ship on the sea level is projected and meshed, and for each mesh region, the global position of the mesh region on the sea chart is determined; According to the speed, amplitude, global angle and frequency of the sea wave, and the global position of the mesh region on the sea chart, the water surface height of the mesh region is determined; According to the water surface height of the mesh region, the moments of the sea wave on the unmanned ship in floating, rolling and pitching are determined; The moments of the sea wave on the unmanned ship in floating, rolling and pitching of each mesh region are accumulated to obtain the moments of the sea wave on the unmanned ship in each dimension.

6. The method of claim 1, wherein, The speed hydrodynamic parameter table of the unmanned ship is obtained, specifically including: Within the range of the throttle of the unmanned ship, for each preset throttle, the speed of the unmanned ship is obtained when the unmanned ship accelerates to uniform linear motion under the corresponding thrust of the throttle in the still water area; According to the relationship between the corresponding thrust of each throttle and the speed of the unmanned ship when accelerating to uniform linear motion, the speed hydrodynamic parameter table of the unmanned ship is established.

7. The method of claim 1, wherein, The roll angle change second-order model of the roll moment drive is modeled according to the speed hydrodynamic parameter table of the unmanned ship and the speed-steering roll angle relationship, and the steering characteristics of the unmanned ship are fitted, specifically including: According to the speed hydrodynamic parameter table of the unmanned ship, the forward direction speed steady state value after full rudder steering at different speeds of the forward direction of the unmanned ship is obtained; According to the forward direction speed steady state value after full rudder steering at different speeds of the forward direction of the unmanned ship and the speed-steering roll angle relationship of the unmanned ship, the roll angle change second-order model of the roll moment drive is established; The first damping parameter in the roll angle change second-order model is calibrated by the final value theorem of the second-order system Laplace transform to obtain the corresponding relationship between the forward direction speed of the unmanned ship and the first damping parameter, which is used as the fitting result of the steering characteristics of the unmanned ship.

8. The method of claim 1, wherein, The pitch angle change second-order model of the pitch moment drive is modeled according to the speed hydrodynamic parameter table of the unmanned ship and the speed-pitch angle relationship, and the pitch characteristics of the unmanned ship are fitted, specifically including: According to the speed hydrodynamic parameter table of the unmanned ship, the forward direction speed steady state value after full rudder steering at different speeds of the forward direction of the unmanned ship is obtained; According to the steady value of the forward direction speed of the unmanned ship after steering at different speeds in different forward directions and the speed-pitch angle relationship of the unmanned ship, a pitch angle change second-order model of the pitch moment driving is established; The second damping parameter in the roll angle change second-order model is calibrated through the final value theorem of the Lagrange transformation of the second-order system, and the corresponding relationship between the forward direction speed of the unmanned ship and the second damping parameter is obtained as the fitting result of the pitch characteristics of the unmanned ship.

9. A device for modeling a dynamic model for unmanned surface vehicle safety testing simulation, characterized in that, The method comprises the following steps: An acquisition module is configured to acquire initial simulation parameters of safety test simulation of the unmanned ship and determine a global pose of the unmanned ship on a sea chart; The initial simulation parameters include unmanned ship information and sea wave information; A control module is configured to acquire control data of the unmanned ship according to a driving mode of the unmanned ship, and determine driving forces and moments of the unmanned ship in each dimension under driving of the control data according to the unmanned ship information and the sea wave information; A sea wave influence module is configured to determine a relative wave height of a center point of the unmanned ship according to the sea wave information and the global pose of the unmanned ship on the sea chart, so as to determine moments of the sea wave on each dimension of the unmanned ship; A dynamics solving module is configured to solve a dynamics model constructed according to the unmanned ship information, the global pose, the driving forces and moments of the unmanned ship in each dimension under driving of the control data, the moments of the sea wave on each dimension of the unmanned ship, and fitting results of steering characteristics and pitch characteristics of the unmanned ship, so as to determine accelerations, speeds and positions of the unmanned ship in each dimension. The fitting result of the steering characteristics of the unmanned ship is obtained by modeling a roll angle change second-order model of roll moment driving according to a speed hydrodynamic parameter table and a speed-steering roll angle relationship, so as to fit the steering characteristics of the unmanned ship; and the fitting result of the pitch characteristics of the unmanned ship is obtained by modeling a pitch angle change second-order model of pitch moment driving according to the speed hydrodynamic parameter table and a speed-pitch angle relationship, so as to fit the pitch characteristics of the unmanned ship.

10. A computer device, comprising: The computer program is stored in the memory and can be run on the processor, and the processor implements the method of any one of claims 1-8 when executing the program. The computer program is stored in the memory and can be run on the processor, and the processor implements the method of any one of claims 1-8 when executing the program.

Images