A method for steering control of an amphibious vehicle in water travel

Abstract

The application is suitable for the field of vehicle engineering and ship control technology, and provides a water navigation turning control method for an amphibious vehicle. The method aims to solve the problems of slow response, low precision and poor stability of the existing water turning control of the amphibious vehicle. The method comprises the following steps: establishing a vehicle dynamics model; obtaining real-time state parameters and a preset target of the vehicle; calculating a target thrust instruction through a controller; inputting the instruction into the dynamics model to predict the turning response of the vehicle, and based on the comparison result of the predicted response and the preset target, if the preset condition is not met, adjusting the controller online and recalculating the instruction until the condition is met; finally, controlling each propulsion unit to generate differential thrust according to the target thrust instruction that meets the condition to complete the turning. By introducing model prediction and online optimization closed loop, the instruction is verified and optimized before execution, which effectively overcomes environmental interference, improves the precision, robustness and adaptive ability of the turning control, and enhances the navigation safety.

Description

Technical Field

[0001] This invention belongs to the fields of vehicle engineering and ship control technology, and particularly relates to a method for controlling the water navigation and steering of an amphibious vehicle. Background Technology

[0002] Amphibious vehicles, possessing both land mobility and water navigation capabilities, play a crucial role in emergency rescue, military operations, and special tasks. However, steering control during water navigation presents a significant technical challenge. The aquatic environment, including waves and currents, introduces strong nonlinear disturbances to vehicles. Traditional steering mechanisms, such as mechanical rudders or simple waterjet propulsion devices, often suffer from sluggish response and control effectiveness highly dependent on speed, easily leading to directional overshoot or instability.

[0003] In existing technologies, some solutions achieve water steering by designing special wheel structures, such as rotatable wheels with paddles. This approach uses a control unit to directly adjust the steering angle and rotational speed of the paddle wheel based on information such as water depth and current to drive the vehicle's steering. While this method can achieve basic steering in low-speed, stable waters, it is essentially a direct open-loop or simple closed-loop control. When facing high-speed navigation or complex, turbulent waters, the lack of accurate prediction of vehicle dynamic response and adaptive adjustment of control strategies makes it difficult to guarantee the accuracy, response speed, and stability of steering control, failing to meet high standards of handling and safety. Therefore, existing amphibious vehicles generally suffer from problems such as sluggish response, low control accuracy, poor stability, and difficulty in adapting to dynamically changing operating conditions when navigating water. Summary of the Invention

[0004] The purpose of this invention is to provide a method for controlling the water navigation and steering of an amphibious vehicle, aiming to solve the technical problems existing in the prior art as identified in the background art.

[0005] This invention is implemented as follows: a method for controlling the water navigation and steering of an amphibious vehicle, the method comprising:

[0006] Step 1: Construct a dynamic model of the amphibious vehicle when it is navigating on water;

[0007] Step 2: Based on the dynamic model, the current navigation status information of the amphibious vehicle is fused in real time, and the desired turning angle is calculated by combining it with the preset target position information;

[0008] Step 3: Calculate the force required by the left and right jet pump thrusters as the thruster force based on the difference between the desired steering angle and the actual steering angle;

[0009] Step 4: Input the current amphibious vehicle state parameters and the calculated propulsion force into the dynamic model to verify the steering effect. If the steering effect does not meet the preset conditions, adjust the calculation parameters of the propulsion force and recalculate.

[0010] Step 5: Convert the calculated thruster force into a control signal and output it to the left and right jet pump thrusters. By adjusting the thrust magnitude and direction of the left and right jet pump thrusters, the amphibious vehicle is driven to steer.

[0011] Furthermore, the dynamic model is an 8-degree-of-freedom dynamic model that includes six motion modes: sway, roll, heave, pitch, roll, and yaw, as well as left and right yaw caused by the difference in operation of the left and right jet pumps.

[0012] Furthermore, the force required for the left and right jet pump thrusters is calculated as the thruster force, and the controller used for the calculation is a PID controller.

[0013] Furthermore, the criterion for determining if the steering effect does not meet the preset conditions is as follows:

[0014] The current amphibious vehicle state parameters and the calculated propulsion force are input into the dynamic model to predict the steering angle. The difference between the predicted steering angle and the desired steering angle is calculated. If the difference is greater than a preset threshold, it is identified as the steering effect not meeting the preset conditions.

[0015] Furthermore, the preset threshold is 0.05 rad.

[0016] Furthermore, the method for driving the amphibious vehicle to steer is as follows:

[0017] Based on the control signal, the current frequency and voltage are adjusted by the motor controller to adjust the water spray volume of the jet pump propulsion unit and the output torque of the motor, thereby controlling the steering of the amphibious vehicle.

[0018] The beneficial effects of this invention are:

[0019] This application introduces a core closed-loop optimization mechanism of "model prediction-online adjustment," enabling the control system to predict the execution effect when issuing commands and iteratively optimize the control command for the next moment based on the difference between the predicted result and the target. This forward-looking verification and correction capability effectively overcomes nonlinear interference from complex environments such as water flow and waves, significantly improving the accuracy of steering control and system robustness, and avoiding heading overshoot or oscillation. Furthermore, unlike traditional controllers that rely on fixed parameters, this application can adjust controller parameters or update the control law online based on the difference between the model prediction result and the target, achieving real-time adaptation of the control strategy to the current operating conditions and reducing reliance on manual parameter tuning. Ultimately, through model-based precise decision-making and closed-loop optimization, the system achieves faster dynamic response and a smoother control process, significantly enhancing the vehicle's maneuverability and agility when turning on water, thereby improving overall navigation safety. Attached Figure Description

[0020] Figure 1 A diagram of a steering control architecture based on a dynamic model provided in an embodiment of the present invention;

[0021] Figure 2 This is a structural diagram of the power system of an amphibious heavy-duty transport vehicle. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0023] like Figure 1 As shown, a method for controlling the water navigation and steering of an amphibious vehicle includes:

[0024] Step 1: Construct a dynamic model of the amphibious vehicle when it is navigating on water;

[0025] When building a dynamic model of an amphibious vehicle, it is necessary to cover six motion modes of the amphibious vehicle when it is navigating on water: swaying, rolling, heaving, pitching, tilting, and yawing. These six basic motions are coupled with each other, and the occurrence of any one motion may cause one or more other motions.

[0026] Based on the traditional 6-DOF (swell, roll, heave, pitch, roll, and yaw) mathematical model of a ship, this model additionally calculates two independent yaw motions caused by the difference in the working states of the left and right jet propulsion units, thus forming an 8-DOF system.

[0027] The design and water control system of amphibious vehicles aim to control these movements as much as possible, especially yaw (controlling direction) and suppressing excessive pitch / roll, thereby ensuring stability and comfort for safe and efficient water navigation. There are also two additional degrees of freedom: left and right yaw, caused by the difference in operation of the left and right jet propulsion pumps. This comprehensive consideration of multiple degrees of freedom more realistically reflects the complex motion of the vehicle on water.

[0028] During model building, key physical parameters of the vehicle itself are deeply integrated. At the same time, complex hydrodynamic factors are fully considered. Wave-making drag can be estimated using calculation methods based on potential flow theory, combined with parameters such as the vehicle's hull shape, speed, and water depth; form drag and friction drag can be determined using boundary layer theory, based on factors such as the surface roughness of the vehicle body, the viscosity of water, and the relative speed between the vehicle and the water.

[0029] The core of this model lies in its ability to mathematically characterize the yaw motion characteristics of a vehicle, i.e., its steering response. Specifically, the yaw motion of an amphibious vehicle is described by the following mathematical equation:

[0030] ;

[0031] : Moment of inertia of the vehicle body about its axis;

[0032] Yaw acceleration;

[0033] Linear hydrodynamic coefficient;

[0034] : Nonlinear hydrodynamic coefficient;

[0035] : Vehicle body sway speed;

[0036] : Yaw rate;

[0037] The difference in yaw moment generated by the left and right jet pump propulsion units;

[0038] Wave interference torque;

[0039] By numerically discretizing the equation, it is possible to calculate the vehicle's yaw rate, angular acceleration, and other state parameters in real time, providing a theoretical basis for the dynamic control of the jet pump vector propulsion system.

[0040] Step 2: Based on the dynamic model, the current navigation status information of the amphibious vehicle is fused in real time, and the desired turning angle is calculated by combining it with the preset target position information;

[0041] The thrust of the left and right jet pumps Real-time feedback is provided by the injection pump; vehicle speed The speed can be accurately measured by vehicle speed sensors installed on the wheels or axles, and the accuracy of the measurement directly affects the accuracy of steering control; yaw angle This information can be obtained using a high-precision electronic compass or GNSS combined with an inertial navigation system to ensure accurate perception of the vehicle's current direction of travel; yaw rate. The gyroscope accurately measures and provides crucial dynamic parameters for vehicle steering control. Specifically, the calculation uses the vehicle's current real-time position information. Based on the preset target position information, a trajectory planning algorithm is used to calculate the desired heading change. The optimal path from the current position to the target position is planned, thus determining the desired heading change. This heading change is then used as input, combined with the vehicle's real-time navigation status information, and substituted into an 8-DOF dynamics model. The Runge-Kutta method is used for iterative solution to accurately calculate the desired steering angle required to achieve the heading change, providing a precise target value for subsequent steering control.

[0042] Step 3: Calculate the force required by the left and right jet pump thrusters as the thruster force based on the difference between the desired steering angle and the actual steering angle;

[0043] Using the vehicle's steering sensors, the actual steering angle is acquired in real time. Based on the difference between the desired and actual steering angles, a PID control algorithm is applied to calculate the force required by the left and right jet propulsion units. .

[0044] By using a proportional term to quickly respond to steering deviation, an integral term to eliminate steady-state error, and a derivative term to predict the trend of deviation change, the force distribution of the left and right jet pump propulsion units is calculated in a comprehensive manner, enabling the vehicle to adjust towards the desired steering angle.

[0045] Step 4: Input the current amphibious vehicle state parameters and the calculated propulsion force into the dynamic model to verify the steering effect. If the steering effect does not meet the preset conditions, adjust the calculation parameters of the propulsion force and recalculate.

[0046] The current vehicle position, speed, heading angle, yaw rate, and calculated left and right thruster forces are input into the vehicle dynamics model to predict the vehicle's steering effect under these forces, including changes in parameters such as the vehicle's trajectory, heading angle, and yaw rate. The predicted steering angle is compared with the expected steering angle. If the difference is less than the threshold of 0.05 rad, it is within the acceptable error range, indicating that the steering effect meets expectations and no adjustment of the PID algorithm parameters is needed. If the difference exceeds the error range, the PID algorithm parameters need to be adjusted, the thrust distribution recalculated, and the verification repeated until the error is within the allowable range.

[0047] Step 5: Convert the calculated thruster force into a control signal and output it to the left and right jet pump thrusters. By adjusting the thrust magnitude and direction of the left and right jet pump thrusters, the amphibious vehicle is driven to steer.

[0048] The calculated thrust from the left and right injection pumps is converted into corresponding control signals and output to the left and right injection pump thrusters. These two thrusters, acting as the core steering actuators, achieve precise vehicle steering control by accurately adjusting the magnitude and direction of their thrust.

[0049] When the vehicle needs to turn right, the control system responds quickly, reducing the motor speed of the left-side jet pump propeller via the motor controller, thereby decreasing its thrust output; simultaneously, it increases the motor speed of the right-side jet pump propeller, increasing its thrust output. This results in a greater thrust on the right side of the vehicle than on the left, generating a rightward steering torque that propels the vehicle to turn right. Conversely, when the vehicle needs to turn left, the control system operates in the opposite direction, reducing the thrust of the right-side jet pump propeller and increasing the thrust of the left-side jet pump propeller, generating a leftward steering torque to complete the left turn.

[0050] The thrust adjustment of the spray pump propulsion system is achieved through precise control of the spray pump motor. The motor controller employs advanced vector control technology, enabling it to precisely change the input current frequency and voltage of the motor according to commands from the control system. By precisely adjusting the current frequency, linear control of the motor speed can be achieved, thereby accurately adjusting the spray volume of the pump. Simultaneously, by adjusting the voltage, the output torque of the motor can be optimized, ensuring stable and efficient operation of the spray pump under various working conditions. For example, when the vehicle is traveling at high speed and requires greater steering torque, the motor controller increases the input voltage, increasing the motor's output torque, allowing the spray pump to operate at higher power and output greater thrust. When the vehicle is traveling at low speed or making minor steering adjustments, the motor controller precisely controls the current frequency, achieving fine adjustments to the spray pump speed, thereby precisely controlling the thrust to meet the needs of precise vehicle steering.

[0051] like Figure 2 As shown, the power system of an amphibious heavy-duty transport vehicle mainly consists of components such as an engine, clutch, ISG motor, transfer case, drive motor, transmission, hub motor, jet pump propulsion unit, and power battery. This invention discloses a waterborne steering control method for amphibious vehicles based on a vehicle dynamics model. Based on the dynamics model, it integrates target heading and sensor-collected information, with the steering controller controlling the left and right jet pump propulsion units and making real-time adjustments according to different water environments and driving states to achieve differential steering. This enhances the handling and stability of the amphibious vehicle, ensuring its safety and efficiency during waterborne navigation; and improves the steering control capability of amphibious vehicles during waterborne navigation.

[0052] 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 specification.

[0053] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for controlling the water navigation and steering of an amphibious vehicle, characterized in that, The method includes: Step 1: Construct a dynamic model of the amphibious vehicle when it is navigating on water; Step 2: Based on the dynamic model, the current navigation status information of the amphibious vehicle is fused in real time, and the desired turning angle is calculated by combining it with the preset target position information; Step 3: Calculate the force required by the left and right jet pump thrusters as the thruster force based on the difference between the desired steering angle and the actual steering angle; Step 4: Input the current amphibious vehicle state parameters and the calculated propulsion force into the dynamic model to verify the steering effect. If the steering effect does not meet the preset conditions, adjust the calculation parameters of the propulsion force and recalculate. Step 5: Convert the calculated thruster force into a control signal and output it to the left and right jet pump thrusters. By adjusting the thrust magnitude and direction of the left and right jet pump thrusters, the amphibious vehicle is driven to steer. The dynamic model is an 8-degree-of-freedom dynamic model that includes six motion modes: sway, roll, heave, pitch, roll, and yaw, as well as left and right yaw caused by the difference in operation of the left and right jet pumps. The lateral motion of the amphibious vehicle is described by the following mathematical equation: ； : Moment of inertia of the vehicle body about its axis; Yaw acceleration; Linear hydrodynamic coefficient; : Nonlinear hydrodynamic coefficient; : Vehicle body sway speed; : Yaw rate; The difference in yaw moment generated by the left and right jet pump propulsion units; Wave disturbance torque; By numerically discretizing the equation, it is possible to calculate the vehicle's yaw rate, angular acceleration, and other state parameters in real time, providing a theoretical basis for the dynamic control of the jet pump vector propulsion system.

2. The method according to claim 1, characterized in that, The force required for the left and right jet pump thrusters is calculated as the thruster force, and the controller used for the calculation is a PID controller.

3. The method according to claim 1, characterized in that, The criterion for determining whether the steering effect does not meet the preset conditions is as follows: The current amphibious vehicle state parameters and the calculated propulsion force are input into the dynamic model to predict the steering angle. The difference between the predicted steering angle and the desired steering angle is calculated. If the difference is greater than a preset threshold, it is identified as the steering effect not meeting the preset conditions.

4. The method according to claim 3, characterized in that, The preset threshold is 0.05 rad.

5. The method according to claim 1, characterized in that, The specific method for driving the amphibious vehicle to steer is as follows: Based on the control signal, the current frequency and voltage are adjusted by the motor controller to adjust the water spray volume of the jet pump propulsion unit and the output torque of the motor, thereby controlling the steering of the amphibious vehicle.

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