Vertical plane navigation attitude control method for variable mass underwater vehicle

Abstract

The invention belongs to the technical field of underwater vehicle control, and particularly relates to a vertical plane navigation attitude control method for a variable-mass underwater vehicle, which can effectively maintain a depth control attitude, reduce energy consumption and improve a voyage, and is beneficial to exerting the optimal maneuvering performance and maneuvering performance of the underwater vehicle. Aiming at the problems of increased navigation resistance, increased energy consumption, increased depth control error and shortened voyage caused by changes of a navigation pitch angle and a rudder angle due to factors such as fuel consumption, cross-sea-area seawater temperature, salinity change and large-range depth change of an underwater vehicle, the invention can effectively maintain a depth control attitude, reduce energy consumption and improve voyage, and has the advantages of simple structure, low cost and high efficiency. And the optimal maneuvering performance and maneuvering performance of the underwater vehicle can be developed. By combining a buoyancy balance control strategy with navigation control, a depth control attitude is kept, so that the energy consumption of vertical plane navigation control is remarkably reduced, the control precision is remarkably improved, and the optimal maneuverability and maneuverability of the underwater vehicle are favorably exerted.

Description

Technical Field

[0001] This invention belongs to the field of underwater vehicle control technology, specifically relating to a method for vertical plane navigation attitude control of a variable mass underwater vehicle. Background Technology

[0002] Submersible vehicles (UVs) have wide applications in civilian and military fields such as marine resource development, hydrographic surveying, underwater reconnaissance, and underwater warfare, and are developing towards greater depth and longer range. Large variable-mass UVs combine electric and thermal power in their propulsion systems to meet the demands of extremely long ranges of thousands or even tens of thousands of nautical miles. However, during long-duration missions, long-range UVs experience changes in their static equilibrium state due to fuel consumption, variations in seawater temperature and salinity across different sea areas, changes in seawater density caused by large-scale depth variations, and deformation of the UV itself. Consequently, certain pitch and rudder angles are required to balance the external forces and torques caused by these buoyancy changes, leading to increased drag, increased energy consumption, increased depth control errors, and reduced range, which negatively impacts the UV's maneuverability, safety, stealth, and energy efficiency. Therefore, optimizing the navigation attitude of variable-mass UVs is one of the key technologies for reducing energy consumption and increasing range.

[0003] Currently, large submersibles with long ranges are equipped with buoyancy adjustment devices. However, due to various complex factors such as fuel consumption, changes in seawater temperature, salinity, and depth across different sea areas leading to changes in seawater density, and deformation of the submersible itself, it is still not possible to fully and effectively solve the problems of increased energy consumption and shortened range caused by changes in navigation attitude. Summary of the Invention

[0004] In view of this, the present invention provides a vertical plane navigation attitude control method for a variable mass underwater vehicle, which can effectively maintain depth control attitude, reduce energy consumption and increase range, and help to give full play to the optimal handling and maneuverability of the underwater vehicle.

[0005] To achieve the objectives of this invention, the following technical solutions are provided.

[0006] A method for vertical plane navigation attitude control of a variable mass underwater vehicle includes the following steps: The speed of the submersible is controlled by the main thruster controlled by the navigation controller. The horizontal rudder of the submersible is controlled by the navigation controller to achieve depth and pitch angle control. The buoyancy adjustment device of the submersible is controlled by a comprehensive buoyancy control strategy to achieve adaptive buoyancy adjustment control of the submersible. The comprehensive buoyancy control strategy includes at least a CTD detection algorithm based on the detection of seawater density changes by a temperature, salinity, and depth (CTD) sensor, a navigation attitude detection algorithm based on online estimation of net buoyancy based on navigation attitude, and a gas turbine estimation algorithm based on fuel consumption to estimate weight loss. The navigation controller switches and combines the three algorithms according to the navigation state and conditions.

[0007] Specifically, the buoyancy adjustment device controlled by the comprehensive buoyancy control strategy includes: When the CTD sensor detects a change in seawater density, the CTD detection algorithm is activated first. The navigation controller calculates the corresponding change in buoyancy based on the change in seawater density and controls the bow and stern buoyancy adjustment devices to perform water injection or drainage actions. When the CTD sensor does not detect a change in seawater density, and the pitch angle and rudder angle of the submersible are greater than the set threshold, if the submersible is in a constant speed, constant depth, and constant heading angle state, and the speed is within the preset range, the navigation attitude detection algorithm is activated to estimate the net buoyancy and buoyancy moment online, and the buoyancy adjustment device is controlled to operate according to the estimated values. When the CTD sensor does not detect a change in seawater density, and the submersible does not meet the requirements of constant speed, constant depth, constant heading angle, or its speed exceeds the preset range, the gas turbine estimation algorithm is activated to estimate the weight loss based on fuel consumption and control the buoyancy adjustment device accordingly.

[0008] The navigation attitude detection algorithm specifically includes: Establish the vertical surface force and moment balance equations for the submersible under constant speed, constant depth, and constant heading angle conditions; Based on the aforementioned equilibrium equation, and according to the currently measured rudder angle and pitch angle, the remaining buoyancy and remaining buoyancy moment of the submersible are calculated online. Based on the remaining buoyancy and remaining buoyancy moment, calculate the required water injection / displacement volume for the bow and stern water tanks, and send commands to control the buoyancy adjustment device to execute the adjustment.

[0009] The preset speed range is greater than 3 knots and less than 20 knots.

[0010] This also includes: After buoyancy compensation is achieved through the buoyancy adjustment device, the pitch angle and rudder angle of the submersible are continuously monitored under constant speed, constant depth, and constant heading angle conditions. When the pitch angle and rudder angle decrease to within the set threshold range, it is determined that the submersible has reached a static equilibrium state, and the buoyancy adjustment device is controlled to stop operating.

[0011] Specifically, after performing buoyancy compensation using the gas turbine estimation algorithm, when the submersible re-enters a constant speed, constant depth, and constant heading angle state and its speed is within a preset range, it switches to the navigation attitude detection algorithm to re-estimate and fine-tune the buoyancy.

[0012] The depth and pitch angle control adopts a cascade control method: the outer loop depth controller calculates the required pitch angle command based on the deviation between the depth command and the current depth value; the inner loop pitch angle controller calculates the required rudder angle command based on the deviation between the pitch angle command and the current pitch angle value, and executes it through the servo motor.

[0013] Beneficial effects 1. This invention addresses the problems of increased drag, energy consumption, depth control error, and reduced range caused by variations in pitch and rudder angles across different sea areas, resulting in increased fuel consumption and variations in seawater temperature, salinity, and depth. It effectively maintains depth control attitude, reduces energy consumption, and increases range, thus facilitating optimal maneuverability and maneuverability of the submersible. By combining buoyancy balance control strategies with navigation control, this invention maintains depth control attitude, significantly reducing energy consumption and improving control accuracy in vertical plane navigation control, thereby facilitating optimal maneuverability and maneuverability of the submersible.

[0014] 2. Traditional submersibles primarily rely on the coordinated operation of propulsion motors and rudders to achieve constant depth navigation. When the submersible's attitude changes due to external ocean environmental factors and variations in its own buoyancy, its energy consumption increases significantly. While buoyancy adjustment devices allow submersibles to adjust their buoyancy to change attitude, thereby significantly reducing energy consumption and increasing endurance, the use of CTD (conductivity, temperature, and depth) sensors during constant depth navigation allows for the detection and calculation of changes in seawater density and corresponding buoyancy. This enables accurate and rapid adaptation to buoyancy changes caused by variations in seawater density across different sea areas and at varying depths. However, this method cannot adjust for changes in the submersible's own buoyancy, such as fuel consumption. Navigation attitude detection algorithms can better estimate the submersible's overall buoyancy changes, improving the accuracy of navigation attitude adjustments.

[0015] 3. In this invention, the underwater vehicle's attitude detection algorithm can only accurately estimate buoyancy changes under conditions of constant depth, constant speed, and constant heading angle. When the underwater vehicle does not meet the navigation conditions in the short term, the gas turbine estimation algorithm is used to directly estimate the weight loss and compensate for buoyancy. When the underwater vehicle meets the navigation conditions again, buoyancy compensation is performed through the attitude detection algorithm. This ensures that the underwater vehicle can maintain a good attitude throughout the entire journey.

[0016] 4. In this invention, the temperature, salinity, and depth (CTD) detection algorithm, the navigation attitude detection algorithm, and the gas turbine estimation algorithm are combined to ensure that the submersible can accurately and quickly adapt to changes in seawater density across sea areas and at varying depths, as well as its own changes, such as changes in buoyancy caused by fuel consumption, throughout the entire navigation process. Attached Figure Description

[0017] Figure 1 This is a schematic diagram showing the composition and distribution of a variable-mass submersible to which the method of this invention applies. In the diagram, 1-bow buoyancy adjustment device, 2-inertial navigation system, 3-depth gauge, 4-fuel, 5-stern buoyancy adjustment device, and 6-servo motor.

[0018] Figure 2 This is a block diagram illustrating the principle of vertical attitude control for a vehicle according to the method of the present invention.

[0019] Figure 3 This is a flowchart of the buoyancy integrated controller control strategy of the method of the present invention. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0021] This invention provides a method for vertical plane navigation attitude control of a variable-mass underwater vehicle. The variable-mass underwater vehicle to which this method is applicable is, for example... Figure 1 As shown, the variable mass submersible includes a bow buoyancy adjustment device 1, an inertial navigation system 2, a depth gauge 3, fuel 4, a stern buoyancy adjustment device 5, and a steering gear 6. The bow buoyancy adjustment device includes a seawater pump, a motor, a valve assembly, and a bow water tank; the inertial navigation system includes an inertial navigation system and a Doppler log (DVL); the fuel includes diesel or liquid oxygen.

[0022] The method of the present invention includes the following steps: The speed of the submersible is controlled by the main propulsion engine controlled by the navigation controller. The depth and pitch angle of the underwater vehicle can be controlled by manipulating the horizontal rudder of the navigation controller. The buoyancy adjustment device is controlled by a comprehensive buoyancy control strategy to achieve adaptive buoyancy adjustment control of the submersible. The comprehensive buoyancy control strategy consists of three parts: a CTD detection algorithm, a navigation attitude detection algorithm, and a gas turbine estimation algorithm. These three parts are switched and combined through certain constraints and logical relationships. The basic implementation method is as follows.

[0023] During navigation, when the density of seawater changes, the temperature, salinity, and depth (CTD) sensor detects and calculates the change in seawater density. The navigation controller then calculates the corresponding change in buoyancy based on the change in seawater density and controls the bow and stern buoyancy adjustment devices to perform the corresponding water injection and dewatering actions to maintain the static balance of the submersible.

[0024] During navigation, when the seawater density remains unchanged (i.e., the CTD sensor does not detect any change in seawater density), the pitch and rudder angles of the submersible change. When the submersible is in a constant speed, constant depth, and constant course state, with a speed greater than 3 knots but less than 20 knots, the navigation controller uses a navigation attitude detection algorithm to estimate the net buoyancy and buoyancy moment online in real time. Based on the estimated net buoyancy, the controller controls the bow and stern buoyancy adjustment devices to perform corresponding water injection and dewatering actions to maintain the static balance of the submersible.

[0025] During navigation, if the seawater density does not change (i.e., the CTD sensor does not detect a change in seawater density), the pitch angle and rudder angle of the submersible will change. Furthermore, if the submersible is not in a state of constant speed, constant depth, and constant heading angle, the submersible will estimate the weight loss based on the gas turbine system. The navigation controller will then control the bow and stern buoyancy adjustment devices to perform corresponding water injection and dewatering actions to maintain the static balance of the submersible.

[0026] When the pitch and rudder angles of a submersible decrease to a certain threshold range while maintaining constant speed, depth, and heading, it indicates that the submersible has reached a state of static equilibrium. The buoyancy control system then stops the water injection and dewatering processes.

[0027] The method based on the navigation attitude detection algorithm is as follows: establish the vertical plane balance equation of the submersible under constant speed, constant depth, and constant heading angle; calculate the remaining buoyancy and remaining buoyancy moment of the submersible based on the rudder angle and pitch angle of the submersible under the conditions of constant depth, constant orientation, and stable speed, and control the buoyancy adjustment device to stop the water injection and water discharge actions.

[0028] The method of this invention is based on a vehicle control algorithm, which includes a depth control algorithm, a speed control algorithm, and a buoyancy integrated adjustment control algorithm.

[0029] The depth control algorithm, through the navigation controller manipulating the underwater vehicle's horizontal rudder, achieves cascaded control of the underwater vehicle's depth and pitch angle, and controls the vertical motion by manipulating the horizontal rudder. Specifically, the depth controller receives depth commands and, based on the current depth value detected by the depth gauge, uses a PID algorithm to calculate the pitch angle command required to reach the set depth. The pitch angle controller uses the pitch angle calculated by the depth controller as input commands and, based on the current pitch angle value detected by the inertial navigation system, uses a PID algorithm to calculate the rudder angle command required to reach the set pitch angle. Finally, the servo motor completes the rudder angle control.

[0030] The speed control algorithm described herein controls the speed of the submersible's main propeller by controlling the rotational speed of the main propeller through the navigation controller. Specifically, the speed controller receives speed commands, calculates the required main propeller rotational speed based on the current speed detected by the inertial navigation system (INS), and uses an incremental PID algorithm to determine the speed needed to reach the set speed. Finally, the main propeller controls the speed.

[0031] The buoyancy integrated control algorithm shown consists of three parts: a CTD detection algorithm, a navigation attitude detection algorithm, and a gas turbine estimation algorithm. These three parts are switched and combined through certain constraints and logical relationships. The buoyancy integrated controller control strategy of this invention is as follows: Figure 3 As shown.

[0032] Operating Condition 1: In the buoyancy integrated adjustment algorithm, the CTD detection algorithm has the highest priority. During the submersible's navigation, the seawater density changes. The CTD sensor detects and calculates the change in seawater density. The navigation controller calculates the corresponding change in buoyancy based on the change in seawater density and controls the bow and stern buoyancy adjustment devices to perform the corresponding water injection and dewatering actions to maintain the submersible's static balance.

[0033] Condition 2: In the buoyancy integrated adjustment algorithm, the navigation attitude detection algorithm has the second highest priority. During the navigation process, the seawater density does not change, that is, the CTD sensor does not detect any change in seawater density. When the pitch angle and rudder angle of the submersible are greater than the set threshold, and the submersible is in a constant speed, constant depth, and constant heading state, with a speed greater than 3 knots and less than 20 knots, the navigation controller uses the navigation attitude detection algorithm to estimate the net buoyancy and buoyancy moment online in real time. Based on the estimated net buoyancy, the controller controls the bow and stern buoyancy adjustment devices to perform corresponding water injection and drainage actions to maintain the static balance of the submersible.

[0034] Condition 3: The gas turbine estimation algorithm takes priority again in the buoyancy integrated adjustment algorithm. During navigation, the seawater density remains unchanged, meaning the CTD sensor does not detect any change in seawater density. When the submersible's pitch and rudder angles change, and the submersible is not in a constant speed, depth, or course state, or its speed is less than 3 knots or greater than 20 knots, the submersible estimates the weight loss based on the gas turbine system. The navigation controller then controls the bow and stern buoyancy adjustment devices to perform corresponding water injection and dewatering actions to maintain the submersible's static balance.

[0035] Condition 4: After buoyancy adjustment is completed in Condition 2, if the pitch angle and rudder angle of the submersible are still greater than the set threshold, and the submersible is in a constant speed, constant depth, and constant heading state with a speed between 3 knots and 20 knots, the navigation controller will again use the navigation attitude detection algorithm to estimate the net buoyancy and buoyancy moment online in real time. Based on the estimated net buoyancy, the bow and stern buoyancy adjustment devices will be controlled to perform corresponding water injection and drainage actions to restore the static balance of the submersible.

[0036] Condition 5: When the pitch and rudder angles of the submersible decrease to a certain threshold range under constant speed, depth, and heading conditions, it indicates that the submersible has reached a state of static equilibrium. Control the buoyancy adjustment device to stop water injection and dewatering.

[0037] The CTD detection algorithm refers to the process where, during the submersible's navigation, when the density of seawater changes, the temperature, conductivity, and depth of the seawater are detected by a temperature, conductivity, and depth sensor. The buoyancy controller then calculates the change in seawater density, calculates the corresponding change in buoyancy based on the change in seawater density, calculates the required water injection and drainage volume, and controls the bow and stern buoyancy adjustment devices to perform the corresponding water injection and drainage actions to maintain the submersible's static balance.

[0038] The aforementioned gas turbine estimation algorithm refers to the change in the weight of the submersible during navigation as fuel such as diesel is consumed. The buoyancy integrated controller calculates the weight change of the submersible based on the consumed fuel, calculates the required water injection and drainage volume, and controls the bow and stern buoyancy adjustment devices to perform corresponding water injection and drainage actions to maintain the static balance of the submersible.

[0039] The specific method of the vehicle attitude detection algorithm is as follows: First, establish the vertical plane equilibrium equations for the submersible under constant speed, constant depth, and constant heading angle conditions. Equation (1) is the resultant force equation for the vertical plane of the submersible, and Equation (2) is the resultant moment equation for the vertical plane. (1) (2) In equations (1) and (2), For rudder lift, For rudder lift torque, For the underwater vehicle to have zero lift, For the underwater vehicle to have zero lift torque, For the angle of attack of the submarine Lift at that time For the angle of attack of the submarine Lift torque at that time To correct the torque, The thrust torque exerted by the thruster on the underwater vehicle, The remaining buoyancy, This represents the remaining buoyancy moment.

[0040] (3) (4) (5) (6) (7) (8) In equations (3) to (8), —Hydrodynamic lift coefficient; —Hydrodynamic torque coefficient; —Seawater density; —Submarine speed; —Submarine vehicle volumetric displacement; The remaining buoyancy and remaining buoyancy moment based on the navigation attitude estimation algorithm are: (9) In the formula, the coefficients ( () represents the equilibrium constant, and the specific formula is as follows: (10) (11) in, express Hydrodynamic displacement of the submersible (L); express The hydrodynamic displacement of the hull (L); express The water pressure (L) of the hull's hydrodynamic torque; express The pressurized water volume (L) of the stern rudder hydrodynamic torque.

[0041] Given that the remaining buoyancy and the remaining buoyancy moment are respectively and Calculate the required injection or discharge volume (11) according to formula (9).

[0042] (12) (13) In the formula, The density of seawater, It is the acceleration due to gravity. The remaining buoyancy corresponds to the required volume of seawater to be injected or discharged. The remaining buoyancy moment corresponds to the required volume of seawater to be injected or discharged. The capacity for injecting or discharging seawater into or from the bow ballast tank. The capacity for injecting or discharging seawater into or from the stern water tank. This refers to the distance from the bow water tank to the center of gravity of the aircraft. This refers to the distance between the stern water tank and the center of gravity of the aircraft.

[0043] This invention includes, but is not limited to, the above embodiments. Any equivalent substitutions or partial improvements made under the spirit and principles of this invention shall be considered within the scope of protection of this invention.

Claims

1. A method for vertical plane navigation attitude control of a variable-mass underwater vehicle, characterized in that, Includes the following steps: The speed of the submersible is controlled by the main thruster controlled by the navigation controller. The horizontal rudder of the submersible is controlled by the navigation controller to achieve depth and pitch angle control. The buoyancy adjustment device of the submersible is controlled by a comprehensive buoyancy control strategy to achieve adaptive buoyancy adjustment control of the submersible. The comprehensive buoyancy control strategy includes at least a CTD detection algorithm based on the detection of seawater density changes by a temperature, salinity, and depth (CTD) sensor, a navigation attitude detection algorithm based on online estimation of net buoyancy based on navigation attitude, and a gas turbine estimation algorithm based on fuel consumption to estimate weight loss. The navigation controller switches and combines the three algorithms according to the navigation state and conditions.

2. The vertical plane navigation attitude control method for a variable-mass underwater vehicle according to claim 1, characterized in that, The buoyancy adjustment device controlled by the comprehensive buoyancy control strategy specifically includes: When the CTD sensor detects a change in seawater density, the CTD detection algorithm is activated first. The navigation controller calculates the corresponding change in buoyancy based on the change in seawater density and controls the bow and stern buoyancy adjustment devices to perform water injection or drainage actions. When the CTD sensor does not detect a change in seawater density, and the pitch angle and rudder angle of the submersible are greater than the set threshold, if the submersible is in a constant speed, constant depth, and constant heading angle state, and the speed is within the preset range, the navigation attitude detection algorithm is activated to estimate the net buoyancy and buoyancy moment online, and the buoyancy adjustment device is controlled to operate according to the estimated values. When the CTD sensor does not detect a change in seawater density, and the submersible does not meet the requirements of constant speed, constant depth, constant heading angle, or its speed exceeds the preset range, the gas turbine estimation algorithm is activated to estimate the weight loss based on fuel consumption and control the buoyancy adjustment device accordingly.

3. The vertical plane navigation attitude control method for a variable-mass underwater vehicle according to claim 2, characterized in that, The navigation attitude detection algorithm specifically includes: Establish the vertical surface force and moment balance equations for the submersible under constant speed, constant depth, and constant heading angle conditions; Based on the aforementioned equilibrium equation, and according to the currently measured rudder angle and pitch angle, the remaining buoyancy and remaining buoyancy moment of the submersible are calculated online. Based on the remaining buoyancy and remaining buoyancy moment, calculate the required water injection / displacement volume for the bow and stern water tanks, and send commands to control the buoyancy adjustment device to execute the adjustment.

4. The vertical plane navigation attitude control method for a variable-mass underwater vehicle according to claim 2, characterized in that, The preset speed range is greater than 3 knots and less than 20 knots.

5. The vertical plane navigation attitude control method for a variable-mass underwater vehicle according to any one of claims 1 to 4, characterized in that, Also includes: After buoyancy compensation is achieved through the buoyancy adjustment device, the pitch angle and rudder angle of the submersible are continuously monitored under constant speed, constant depth, and constant heading angle conditions. When the pitch angle and rudder angle decrease to within the set threshold range, it is determined that the submersible has reached a static equilibrium state, and the buoyancy adjustment device is controlled to stop operating.

6. The vertical plane navigation attitude control method for a variable-mass underwater vehicle according to claim 2, characterized in that, After performing buoyancy compensation using the gas turbine estimation algorithm, when the submersible re-enters a constant speed, constant depth, and constant heading angle state and its speed is within a preset range, it switches to the navigation attitude detection algorithm to re-estimate and fine-tune the buoyancy.

7. The vertical plane navigation attitude control method for a variable-mass underwater vehicle according to claim 1, characterized in that, The depth and pitch angle control adopts a cascade control method: the outer loop depth controller calculates the required pitch angle command based on the deviation between the depth command and the current depth value; the inner loop pitch angle controller calculates the required rudder angle command based on the deviation between the pitch angle command and the current pitch angle value, and executes it through the servo motor.

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