Horizontal plane motion control correction method suitable for AUV (Autonomous Underwater Vehicle)

Abstract

The invention discloses a horizontal plane motion control correction method suitable for an AUV (Autonomous Underwater Vehicle). The method comprises the following steps: acquiring ocean current flow velocity and flow direction information in real time by using a Doppler velocimeter DVL carried by the AUV; planning a target course angle and a target navigational speed in the still water environment according to the current position and the target position; decomposing the ocean current velocity into a longitudinal component and a vertical component along the course of the target; performing joint compensation correction on the target course angle and the target navigational speed based on the components to obtain an actual control instruction; and controlling the AUV to execute the corrected motion. Under the condition that a special ocean current sensor is not added, ocean current real-time sensing is achieved by fusing DVL existing data, a feedforward type vector compensation mechanism is adopted, the track tracking precision, spot hover stability and motion control robustness of the AUV in a complex ocean current environment are remarkably improved, and the method is particularly suitable for small and medium-sized AUV platforms with limited loads.

Description

Technical Field

[0001] This invention belongs to the technical field of underwater current measurement, specifically relating to a horizontal plane motion control correction method suitable for AUVs. Background Technology

[0002] Autonomous underwater vehicles (AUVs) are playing an increasingly important role in marine development and national defense due to their numerous advantages, including small size, low operating costs, intelligent autonomous operation, convenient maintenance, and good stealth capabilities. As the application areas of AUVs gradually expand, the requirements for control systems are also increasing, especially the autonomous control capabilities for attitude, trajectory, and hovering in complex ocean current environments, to adapt to operational conditions in such environments. This necessitates that AUVs be able to accurately measure the speed and direction of ocean currents in real time, providing current information to the control system to assist in navigation and motion control, thereby improving their adaptability to operations in complex ocean current environments.

[0003] Currently, small and medium-sized AUVs are generally limited by their payload capacity and do not have the ability to measure ocean currents in real time. Their motion control is easily affected by ocean currents, which reduces the accuracy of motion control and increases the deviation distance of track control. This poses a great challenge, especially for fixed-point directional hovering operations in ocean current environments. Summary of the Invention

[0004] To address the aforementioned shortcomings, this invention proposes a horizontal plane motion control correction method suitable for AUVs, which solves the motion control problem of AUVs in ocean current environments and greatly improves the control capabilities such as hovering and track deviation in ocean current environments, thus having high engineering application value.

[0005] The technical solution for implementing the present invention is as follows: A method for horizontal plane motion control correction applicable to AUVs includes the following steps: S101: Using the Doppler velocity meter (DVL) mounted on the AUV, differential calculations are performed on the speed of the seabed and the speed of the water layer below the vehicle simultaneously acquired by the DVL to obtain the current speed and direction information in real time. S102: Based on the current position and target position of the AUV, plan the target heading angle ψt and target speed Vt in a calm water environment; S103: The ocean current velocity obtained in step S101 is decomposed along the target heading angle ψt planned in step S102 into a longitudinal velocity component Vc‖ parallel to the heading and a lateral velocity component Vc⊥ perpendicular to the heading. S104: The target heading angle ψt and target speed Vt are jointly compensated and corrected using the longitudinal velocity component Vc‖ and the lateral velocity component Vc⊥ to obtain the actual target heading angle ψt' and actual target speed Vt' used to offset the influence of ocean currents; S105: Control the AUV to perform horizontal motion control with the actual control target heading angle ψt' and the actual control target speed Vt'.

[0006] Further, step S101 specifically includes: S1011: Obtain the velocity vector relative to the seabed and the velocity vector relative to the water layer below the vehicle measured by DVL in the DVL carrier coordinate system; S1012: Calculate the difference between the velocity vector to the seabed and the velocity vector to the water layer to obtain the ocean current velocity vector in the DVL carrier coordinate system; S1013: Based on the installation relationship parameters between the DVL and the AUV's inertial navigation system, the ocean current velocity vector in the DVL's carrier coordinate system is transformed to the AUV's carrier coordinate system; S1014: Based on the real-time attitude information provided by the inertial navigation system, the ocean current velocity vector in the carrier coordinate system is transformed to the navigation coordinate system to obtain the velocity component of the ocean current in the navigation coordinate system; S1015: Calculate the magnitude of the scalar velocity and the outflow azimuth relative to geographic north based on the velocity component of the ocean current in the navigation coordinate system.

[0007] Furthermore, in step S102, the planning of the target heading angle ψt and the target speed Vt is based at least on one or more parameters among the real-time position of the AUV, the target position, and the current track tracking error.

[0008] Further, in step S103, the decomposition is based on the geometric relationship between the scalar magnitude Vc of the ocean current velocity, its outflow azimuth angle θc and the target heading angle ψt, respectively obtaining the projection component along the heading as the longitudinal velocity component Vc‖ and the projection component perpendicular to the heading as the lateral velocity component Vc⊥.

[0009] Further, step S104 specifically includes: S1041: Based on the vector relationship formed by the target speed Vt, the longitudinal velocity component Vc‖ and the lateral velocity component Vc⊥, calculate the heading compensation angle required to counteract the lateral drift of the ocean current; S1042: Apply the heading compensation angle to the target heading angle ψt to obtain the actual controlled target heading angle ψt'; S1043: Based on the target speed Vt, the longitudinal velocity component Vc‖ and the lateral velocity component Vc⊥, the actual controlled target speed Vt' is calculated by vector synthesis.

[0010] Furthermore, the specific formula for step S104 is as follows:

[0011]

[0012] in, ψt is the target heading angle in an ideal still water environment under real-time control of the aircraft. The target speed is Vt; and Decompose the ocean currents to the target heading angle. The parallel and perpendicular velocity components, namely Vc‖ and Vc⊥, The corrected target heading angle is ψt'. The corrected target speed is Vt'; Finally, the vehicle's motion control module, with the corrected target heading angle... and target speed To control the course and speed of the aircraft in horizontal motion.

[0013] Beneficial effects: 1. This invention utilizes existing DVL equipment on an AUV to calculate ocean current information in real time and uses it to dynamically correct motion control commands, forming a "measurement-correction" closed loop. This method enables the AUV to actively counteract ocean current disturbances, significantly improving the accuracy and robustness of track tracking and hovering in real ocean current environments.

[0014] 2. This invention indirectly obtains real-time ocean current information by fusing DVL (Depth-to-bottom and depth-to-water) velocity data through an algorithm, eliminating the need for additional large sensors such as ocean current profilers. This method is particularly suitable for small to medium-sized AUVs with limited payloads, significantly enhancing their operational capabilities in complex ocean current environments without substantially increasing cost, power consumption, or size.

[0015] 3. This invention decomposes ocean current velocity into the target heading and performs feedforward correction, enabling the AUV to pre-compensate for lateral drift and velocity loss caused by ocean currents. This method improves the positioning accuracy and track stability of AUVs in ocean observation, mapping, and other tasks, and enhances their operational reliability in dynamic flow fields. Attached Figure Description

[0016] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0017] First, combine Figure 1 This invention describes a method for correcting horizontal plane motion control in real-time ocean current measurement assisted by an AUV, according to one embodiment of the present invention. Figure 1 As shown, the method includes the following steps: Step S101: Use DVL to measure the velocity and direction of the ocean current in real time; Step S102: The vehicle plans the target heading angle and target speed for horizontal motion control based on its current position and target position; Step S103: Decompose the ocean current velocity into longitudinal and lateral velocities along the target heading angle planned in real time; Step S104: Correct the target heading angle and target speed in still water as planned for the mission by adjusting for ocean current effects.

[0018] Step S105: The vehicle performs course control and speed control based on the target heading angle and target speed corrected by the ocean current.

[0019] Step S101: The AUV is configured with a high-precision satellite navigation / INS inertial navigation system / DVL Doppler velocimeter combined navigation system. The Doppler velocimeter has the function of simultaneously measuring bottom velocity and convective velocity relative to the water layer below the transducer. Record the real-time output of the DVL. The velocity relative to the seabed under the system is The speed of the vehicle in the water below it is .

[0020] Then the ocean currents are Speed ​​of the system for: .

[0021] Secondly, the ocean currents in Speed ​​of the system Transform to the inertial navigation carrier coordinate system b. Let the installation error angle between the inertial navigation system and the DVL be . The DVL scaling factor is k ,but: (1) Next, the ocean currents are placed in the inertial navigation carrier coordinate system b. Real-time attitude via inertial navigation , converted Speed ​​of the system ,Right now: (2) (3) (4) (5) in: For real-time heading angle, For real-time pitch angle, The roll angle is given in real time by the inertial navigation system.

[0022] Finally, by the ocean currents Speed ​​of the system Real-time calculation of scalar velocity of ocean currents and the direction of flow from the geography department .

[0023] (6) (7) Will Converting to the geographical system that defines azimuth as "north as 0 and clockwise as positive", the resulting ocean current outflow azimuth is... .

[0024] Step S102: The vehicle plans the target heading angle and target speed for horizontal plane motion control based on the current position and the target position, including: Autonomous horizontal motion control of an AUV is generally divided into hovering and track-keeping control. The control mission planning module plans real-time control target quantities based on the vehicle's current position and speed, target position, and current track yaw distance. Specifically, it provides the control target quantities in real-time under ideal still-water conditions, such as the target heading angle. and target speed .

[0025] Step S103: The ocean current velocity is decomposed longitudinally and laterally along the target heading angle planned in real time, including: All calculations below are performed in a geographic coordinate system where "north is 0 and clockwise is positive".

[0026] Given: scalar velocity of ocean currents and the direction of flow The target heading angle under ideal still water conditions controlled in real time by the aircraft. Target speed The angle of the ocean current speed along the target heading Perform vertical and horizontal decomposition. Then we have: 1. Calculate the direction of ocean currents With the target heading angle Angle between (8) 2. Target heading angle ocean current velocity component

[0027] (9) 3 Vertical target heading angle ocean current velocity component

[0028] (10) Step S104: Correcting the target heading angle and target speed in calm water for ocean current influences in the mission plan, including: Given: The target heading angle under ideal still water conditions controlled in real time by the aircraft. Target speed And the ocean currents decompose to the target heading angle parallel velocity components and vertical velocity components The corrected target heading angle Target speed for: (11) (12) Finally, the vehicle's motion control module, with the corrected target heading angle... and target speed To control the course and speed of the aircraft in horizontal motion.

[0029] This invention further provides a method for correcting horizontal plane motion control in real-time ocean current measurement aids for AUVs, comprising: A processor is used to execute multiple instructions; Memory, used to store multiple instructions; The aforementioned instructions are stored in the memory and loaded and executed by the processor, as described above, for the horizontal plane motion control correction method for real-time ocean current measurement assistance applicable to AUVs.

[0030] The present invention further provides a computer-readable storage medium storing a plurality of instructions; the plurality of instructions are used by a processor to load and execute the horizontal plane motion control correction method for real-time ocean current measurement assisted by the AUV as described above.

[0031] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0032] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for horizontal plane motion control correction suitable for AUVs, characterized in that, Includes the following steps: S101: Using the Doppler velocity meter (DVL) mounted on the AUV, differential calculations are performed on the speed of the seabed and the speed of the water layer below the vehicle simultaneously acquired by the DVL to obtain the current speed and direction information in real time. S102: Based on the current position and target position of the AUV, plan the target heading angle ψt and target speed Vt in a calm water environment; S103: The ocean current velocity obtained in step S101 is decomposed along the target heading angle ψt planned in step S102 into a longitudinal velocity component Vc‖ parallel to the heading and a lateral velocity component Vc⊥ perpendicular to the heading. S104: The target heading angle ψt and target speed Vt are jointly compensated and corrected using the longitudinal velocity component Vc‖ and the lateral velocity component Vc⊥ to obtain the actual target heading angle ψt' and actual target speed Vt' used to offset the influence of ocean currents; S105: Control the AUV to perform horizontal motion control with the actual control target heading angle ψt' and the actual control target speed Vt'.

2. The method according to claim 1, characterized in that, Step S101 specifically includes: S1011: Obtain the velocity vector relative to the seabed and the velocity vector relative to the water layer below the vehicle measured by DVL in the DVL carrier coordinate system; S1012: Calculate the difference between the velocity vector to the seabed and the velocity vector to the water layer to obtain the ocean current velocity vector in the DVL carrier coordinate system; S1013: Based on the installation relationship parameters between the DVL and the AUV's inertial navigation system, the ocean current velocity vector in the DVL's carrier coordinate system is transformed to the AUV's carrier coordinate system; S1014: Based on the real-time attitude information provided by the inertial navigation system, the ocean current velocity vector in the carrier coordinate system is transformed to the navigation coordinate system to obtain the velocity component of the ocean current in the navigation coordinate system; S1015: Calculate the magnitude of the scalar velocity and the outflow azimuth relative to geographic north based on the velocity component of the ocean current in the navigation coordinate system.

3. The method according to claim 1, characterized in that, In step S102, the planning of the target heading angle ψt and the target speed Vt is based at least on one or more parameters among the real-time position of the AUV, the target position, and the current track tracking error.

4. The method according to claim 1, characterized in that, In step S103, the decomposition is based on the geometric relationship between the scalar magnitude Vc of the ocean current velocity, its outflow azimuth angle θc, and the target heading angle ψt, respectively obtaining the projection component along the heading as the longitudinal velocity component Vc‖ and the projection component perpendicular to the heading as the lateral velocity component Vc⊥.

5. The method according to any one of claims 1-4, characterized in that, Step S104 specifically includes: S1041: Based on the vector relationship formed by the target speed Vt, the longitudinal velocity component Vc‖ and the lateral velocity component Vc⊥, calculate the heading compensation angle required to counteract the lateral drift of the ocean current; S1042: Apply the heading compensation angle to the target heading angle ψt to obtain the actual controlled target heading angle ψt'; S1043: Based on the target speed Vt, the longitudinal velocity component Vc‖ and the lateral velocity component Vc⊥, the actual controlled target speed Vt' is calculated by vector synthesis.

6. The method according to claim 5, characterized in that, The specific formula for step S104 is as follows: in, ψt is the target heading angle in an ideal still water environment under real-time control of the aircraft. The target speed is Vt; and Decompose the ocean currents to the target heading angle. The parallel and perpendicular velocity components, namely Vc‖ and Vc⊥, The corrected target heading angle is ψt'. The corrected target speed is Vt'; Finally, the vehicle's motion control module, with the corrected target heading angle... and target speed To control the course and speed of the aircraft in its horizontal movement.

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