A motion control algorithm for a quad-rotor unmanned underwater vehicle

Abstract

The present application relates to underwater robot control technical field, specifically to a kind of four-rotor unmanned underwater vehicle motion control algorithm.The technical scheme used in the present application is: body coordinate system origin is at unmanned underwater vehicle float center, x axis is along the center of rotation of vehicle body and points to head, y axis is in the longitudinal symmetry plane of vehicle, perpendicular to x axis and points to upper, z axis positive direction is determined according to right hand rule method;Including horizontal motion control and pitch plane motion control two parts.The present application adopts the method of dynamically configuring the rotating speed, steering and inclination angle of four propellers, and realizes the forward, backward, lateral motion, floating, diving, hovering and large maneuvering motion of unmanned underwater vehicle by changing the above parameters.The present application combines the unmanned underwater vehicle body with adjustable inclination angle propeller of gyroid shape, and develops a motion control algorithm matched with this structure form, which can realize the underwater six-degree-of-freedom motion and hovering, large maneuvering and other actions of unmanned underwater vehicle.

Description

Technical Field

[0001] This invention relates to the field of underwater robot control technology, specifically a motion control algorithm for a quadcopter unmanned underwater vehicle. Background Technology

[0002] Unmanned underwater vehicles are one of the important pieces of equipment for marine development, monitoring, and ecological protection. By carrying different types of sensors and actuators, they can effectively carry out operations for various tasks such as marine exploration, development, monitoring, and reconnaissance.

[0003] To accomplish specific underwater tasks, unmanned underwater vehicles (UUVs) need to possess the ability to ascend vertically, descend vertically, or hover. When operating in confined spaces, UUVs require high maneuverability. Existing UUVs mostly adopt a rotary body shape, with a propeller and four rudders (in a cross or X shape) at the tail. Such UUVs can only maintain a stable attitude or change attitude at a certain speed, and cannot hover, ascend vertically, or descend vertically. Due to the limitations of the propeller layout, these UUVs cannot perform high-maneuverability maneuvers with small turning radii.

[0004] In recent years, a new type of quadcopter unmanned underwater vehicle (UUV) has emerged, featuring four thrusters fixedly mounted on the vehicle body. This type of UUV adjusts its attitude by changing the rotational speed of the four thrusters. This control method couples speed control and attitude control, limiting the range of attitude angle changes, making it difficult to control during surface missions and hindering high-maneuverability. For example, the streamlined quadcopter UUV based on vector propulsion mentioned in patents CN 108423145 A and CN 110065606 A uses a linkage between the two thrusters of the propulsion device. When encountering interference, this linkage weakens the maneuverability of the propulsion device. The butterfly-shaped quadcopter UUV mentioned in patent CN 302992368 S, based on the characteristics of quadcopter unmanned platforms, relies on adjusting the rotational speed of a fixed thruster to achieve forward motion. Limited by the safe pitch angle, the forward velocity component is small, making it difficult to increase forward speed. During high-speed underwater navigation, the large surface area against the current reduces speed.

[0005] In light of the above, it is necessary to develop a novel unmanned underwater vehicle (UUV) with complete propulsion capabilities, capable of achieving arbitrary six-degree-of-freedom motion. The rotational speed, steering, and tilt angle of the four thrusters relative to the horizontal plane of the vehicle's four propellers in this novel quadcopter-powered UUV are all adjustable. The vehicle has numerous independent control parameters, and its motion modes include depth-holding, orientation-based movement, surfacing, diving, hovering, and high-maneuvering. Furthermore, it is difficult to establish a mathematical model for the vehicle's motion, making existing quadcopter UUV motion control algorithms unsuitable. Therefore, it is necessary to develop motion control algorithms suitable for this novel quadcopter-powered UUV. Summary of the Invention:

[0006] This invention provides a motion control algorithm for a quadcopter unmanned underwater vehicle to overcome the technical problems of existing unmanned underwater vehicles being difficult to control and unable to perform detailed underwater exploration in confined spaces.

[0007] To achieve the objectives of this invention, the technical solution provided by this invention is as follows:

[0008] A motion control algorithm for a quadcopter unmanned underwater vehicle (UUV) is provided. The quadcopter UUV includes four servo motors inside the fuselage and four thrusters symmetrically arranged on both sides of the UUV fuselage. The four thrusters 3 are respectively connected to independently moving servo motors 1 via drive shafts 2. The servo motors 1 are fixed to the propulsion control section housing 4.

[0009] The structural layout of the quadcopter unmanned underwater vehicle is as follows: the origin of the body coordinate system is at the buoyancy center of the unmanned underwater vehicle, the x-axis points to the head along the rotation center of the vehicle body, the y-axis is located in the longitudinal symmetry plane of the vehicle, perpendicular to the x-axis and pointing upwards, and the positive direction of the z-axis is determined by the right-hand rule.

[0010] The control inputs for the quadcopter unmanned underwater vehicle are: the rotational speed of the four thrusters, the forward / reverse signal, and the tilt angle of the thruster plane relative to the horizontal plane of the vehicle body;

[0011] The motion control algorithms include two main categories: horizontal motion control and pitch plane motion control.

[0012] I. Horizontal Motion Control

[0013] 1.1 Surface remote control

[0014] Remote control of the surface uses only the two rear thrusters of the quadcopter unmanned underwater vehicle, and the command speed V of the thrusters is set to speed. d Set the corresponding servo tilt angle d to a fixed value δ. e1 This causes the tail of the quadcopter unmanned underwater vehicle to be completely submerged in the water, i.e.

[0015] V 后推进器 =speed d

[0016] d 后舵机 =δ e1

[0017] 1.2 Underwater navigation motion control

[0018] The underwater navigation of the quadcopter unmanned underwater vehicle is achieved by adjusting the speed and tilt angle of its four thrusters to control its attitude and position.

[0019] (1) Speed ​​distribution:

[0020]

[0021] Among them, V i (i = 1, 2, 3, 4) represents the speed command for the i-th thruster. d This indicates the desired rotational speed command.

[0022] (2) Rudder angle distribution:

[0023]

[0024] Where, d i (i = 1, 2, 3, 4) represents the tilt angle command of the i-th thruster, L1 represents the x-axis position coordinates of the front pair of thrusters, and L2 represents the x-axis position coordinates of the rear pair of thrusters.

[0025] speed in the above formula yaw d e and d d Determined by the following calculation formula.

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033] in,

[0034] e i(i = h, φ, θ, ψ) represents the difference between the command input and the actual output, where h, φ, θ, ψ represent depth, roll angle, pitch angle, and yaw angle, respectively.

[0035] k i (i = ep1, ep2, ed, dp, dd, rp, rd) represents the control gain of the system;

[0036] i0 (i = φ, θ) represents the attitude control reference value;

[0037] δ i (i = de, dd, v) represents a linear interval;

[0038] Indicates attitude angular velocity;

[0039] d i (i = e, d) represents the tilt adjustment command, where e and d represent the tilt distribution command and the tilt differential command, respectively.

[0040] speed yaw This indicates a speed adjustment command.

[0041] II. Tilting Plane Motion Control:

[0042] 2.1 Ascent and Descent Motion Control

[0043] During the ascent and descent control processes, the tilt angle of all four thrusters is at 90°, meaning they are perpendicular to the horizontal plane of the unmanned aerial vehicle (UAV). The rotational speed of the four thrusters is...

[0044]

[0045] in,

[0046]

[0047]

[0048]

[0049]

[0050] Where, k i (i = ph, dh, ih, pθ, dθ, iθ, pφ, dφ, iφ, pψ, dψ, iψ) represents the control gain of the system. ylimit This indicates the lower limit of depth control.

[0051] 2.2 Fixed-point hovering motion control

[0052] hovering motion control is executed under the premise of ascent and descent motion control. When performing hovering, the V-axis in 2.1 ascent and descent motion control is... t Replace with the following:

[0053]

[0054]

[0055] Among them, e h =hh d The depth difference is represented by m, the weight of the quadcopter unmanned underwater vehicle is represented by g, the acceleration due to gravity is represented by V, the displacement volume is represented by ρ, and the density of water is represented by k. pT Indicates the hover control gain, δ T Representing the linear interval, to achieve the hovering requirement, δ can be adjusted according to performance specifications. T To meet control accuracy requirements, under normal circumstances, δ T ∈[-0.5m,0.5m].

[0056] Compared with the prior art, the beneficial effects of the present invention are:

[0057] 1. The quadcopter unmanned underwater vehicle (UUV) of this invention does not alter the fluid dynamics of traditional UUVs. Structural modifications are achieved simply by adding four propulsion units, resulting in a compact structure and low cost. Each of the four propulsion units is coupled to an independently moving servo motor, and the tilt angle of the propulsion units can be adjusted via the servo motor. When performing surface missions, the quadcopter UUV of this invention operates solely through the two propulsion units located near the tail, rotating at a tilt angle δ using these two tail propulsion units. e1 and propulsion speed d It submerges the two propulsion units near the stern into the water to perform surface navigation missions.

[0058] 2. The control algorithm presented in this invention dynamically configures the rotational speed, steering, and tilt angle of the four thrusters according to different motion modes of the unmanned underwater vehicle (UUV). By changing these parameters, it enables the UUV to perform forward, backward, lateral, surfacing, diving, hovering, and large-scale maneuvers involving changes in attitude angle. It can achieve surfacing, diving, and hovering through vertical ascent and descent movements, exhibiting strong maneuverability and flexibility.

[0059] 3. Traditional rotary-shaped unmanned underwater vehicles (UUVs) generally prioritize high-speed underwater navigation performance, neglecting features such as hovering. This invention combines a rotary-shaped UUV body with an adjustable-angle thruster and develops a motion control algorithm compatible with this structural form, enabling high-speed forward travel, large maneuvers, and vertical ascent, descent, and hovering.

[0060] 4. The method of this invention refines the motion modes of the quadcopter underwater vehicle, assigning servo angle, thruster speed, and steering control parameters to different motion modes. The motion control method presented in this invention does not rely on a precise mathematical model of the unmanned underwater vehicle, thus possessing greater practical value. When operating in complex waters with numerous obstacles, this invention can be equipped with various sensors to achieve obstacle perception and avoidance functions. Attached image description:

[0061] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0062] Figure 2 for Figure 1 A schematic diagram of the propulsion control section structure;

[0063] Figure 3 for Figure 2 AA cross-section view;

[0064] Figure 4 This is an exploded view of the motion modes of the present invention.

[0065] The annotations in the attached figures are explained as follows:

[0066] 1-Servo motor, 2-Drive shaft, 3-Thruster, 4-Thrust control section housing. Detailed Implementation

[0067] The present invention will be further illustrated with reference to specific embodiments. The embodiments listed below are for illustrative purposes only and are not intended to limit the scope of the invention.

[0068] This invention provides a motion control algorithm for a quadcopter unmanned underwater vehicle. The quadcopter unmanned underwater vehicle used is described in [reference needed]. Figure 1 and Figure 2 The system includes four servo motors 1 inside the fuselage and four thrusters 3 (numbered 1 and 3 symmetrically arranged at the front and 2 and 4 symmetrically arranged at the rear) symmetrically arranged on the left and right sides of the unmanned underwater vehicle (UUV) fuselage. Each of the four thrusters 3 is connected to an independently moving servo motor 1 via a drive shaft 2. The servo motors 1 are fixed to the inner wall of the propulsion control section housing 4. The tilt angle of each thruster 3 is adjusted by the servo motors 1 inside the fuselage. Each thruster 3 rotates along the drive shaft 2, thereby changing the direction of thrust. By changing the rotational speed of the propellers of each thruster 3, the magnitude of its thrust is changed, thus altering the magnitude and direction of the forces acting on the entire UUV. The rotation range of the servo motor 1's shaft is -180° to +180°.

[0069] The quadcopter unmanned underwater vehicle of this invention has the following structural layout: the origin of the body coordinate system is at the center of buoyancy of the unmanned underwater vehicle; the x-axis points towards the head along the center of rotation of the vehicle body; the y-axis is located within the longitudinal symmetry plane of the vehicle, perpendicular to the x-axis and pointing upwards; the positive direction of the z-axis is determined by the right-hand rule. Figure 1 As shown, the control inputs of the quadcopter unmanned underwater vehicle are: the rotational speed of the four thrusters, the forward / reverse signal, the tilt angle of the thruster plane relative to the horizontal plane, and the servo angle. This invention achieves different modes of movement of the quadcopter unmanned underwater vehicle by controlling the above input quantities.

[0070] The motion control algorithm comprises two main parts: horizontal motion control and pitch plane motion control.

[0071] I. Horizontal Motion Control

[0072] 1.1 Surface remote control

[0073] The quadcopter unmanned underwater vehicle (UUV) uses rear thrusters 2 and 4, while front thrusters 1 and 3 are inactive. Since the roll angle of the quadcopter UUV approaches 0° once it reaches stable navigation, the command rotation speed for thrusters 2 and 4 is set to speed [speed value missing] during surface remote control. d The servo rotation angle of thrusters No. 2 and No. 4 is set to a fixed value δ. e1 This causes the tail of the quadcopter unmanned underwater vehicle to be completely submerged in the water, i.e.

[0074] V 后推进器 =speed d (1)

[0075] d 后舵机 =δ e1 (2)

[0076] Send forward, backward, left turn, and right turn commands via the remote control, and execute T for each command. d Seconds. When moving forward, the propellers of thrusters 2 and 4 turn in the forward direction to push water backward; when moving backward, the propellers of thrusters 2 and 4 reverse direction; when turning left, thruster 4 decelerates and thruster 2 accelerates; when turning right, thruster 4 accelerates and thruster 2 decelerates.

[0077] 1.2 Underwater navigation motion control

[0078] The underwater navigation of the quadcopter unmanned underwater vehicle is controlled by adjusting the speed and tilt angle of its four thrusters to achieve attitude and position control.

[0079]

[0080]

[0081]

[0082]

[0083]

[0084]

[0085]

[0086] in,

[0087] e i (i = h, φ, θ, ψ) represents the difference between the command input and the system response output, where h, φ, θ, ψ represent depth, roll angle, pitch angle, and yaw angle, respectively.

[0088] k i (i = ep1, ep2, ed, dp, dd, rp, rd) represents the control gain of the system;

[0089] i0 (i = φ, θ) represents the attitude control reference value;

[0090] δ i (i = de, dd, v) represents the linear interval

[0091] Indicates attitude angular velocity;

[0092] d i (i = e, d) represents the tilt adjustment command, where e and d represent the tilt distribution command and the tilt differential command, respectively.

[0093] speed yaw This indicates a speed adjustment command.

[0094] Speed ​​distribution:

[0095]

[0096] Among them, V i (i = 1, 2, 3, 4) represents the speed command for the i-th thruster. d This indicates the desired rotational speed command.

[0097] Rudder angle distribution:

[0098]

[0099] Where, d i(i = 1, 2, 3, 4) represents the tilt angle command of the i-th thruster, L1 represents the x-axis position coordinates of thrusters 1 and 3, and L2 represents the x-axis position coordinates of thrusters 2 and 4.

[0100] During underwater navigation, the navigation path is planned in advance according to the test site, and the necessary parameters for each segment of the path are set and saved. When the quadcopter underwater vehicle performs underwater tasks, the GPS data recorded on the water surface and the motion path are used to calculate the underwater latitude and longitude during the motion process, and the command heading angle (Yaw) is obtained through attitude calculation. d Based on the command input and system response output, substitute into equations (3)-(11) to calculate the rotational speed input V of the quadcopter unmanned underwater vehicle. i (i = 1, 2, 3, 4) and rudder angle input d i (i = 1, 2, 3, 4).

[0101] When performing underwater altitude-fixed navigation missions, the quadcopter unmanned underwater vehicle enters the water from the surface, changes the medium, and completes the diving motion. During the motion, the change in medium causes roll, and the diving motion causes pitch. The speed change and roll motion make it difficult to control the attitude. At this time, the collected altitude h needs to be substituted into the following formula (12) for calculation, and then substituted into formulas (3)-(11) to calculate the speed input and rudder angle input.

[0102] h=h*cos(θ)*cos(φ) (12)

[0103] When performing underwater gyratory motion missions, the quadcopter unmanned underwater vehicle sets the gyratory motion radius, speed, depth and desired step according to the mission area, and changes the heading angle by controlling the speed of the thrusters according to equations (7)-(10).

[0104] During the execution of the above tasks, safety restrictions such as exceeding depth, time limits, and range limits were imposed based on the test site, i.e., exceeding the depth limit h. lim Immediately afterwards, the propeller stopped rotating, the servo motor reset, and the entire flight time T was exceeded. lim Stop immediately after passing the test area of ​​the lake or sea.

[0105] II. Tilting Plane Motion Control: For a fixed quadcopter unmanned underwater vehicle, the rudder angle of the servo motor is 90°, and vertical motion is achieved by changing the rotation speed.

[0106] 2.1 Ascent and Descent Motion Control

[0107]

[0108]

[0109]

[0110]

[0111]

[0112] Where, k i (i = ph, dh, ih, pθ, dθ, iθ, pφ, dφ, iφ, pψ, dψ, iψ) represents the control gain of the system. ylimit This indicates the lower limit of depth control. During vertical ascent and descent, the fixed quadcopter unmanned underwater vehicle's rudder angle is 90°. Descent is propelled upwards by commanded rotation speed, while vertical ascent is achieved when the four propellers rotate in opposite directions. Because vertical and horizontal motion control methods differ, the system's control gain cannot be universally applied.

[0113] 2.2 Fixed-point hovering motion control: When the quadcopter unmanned underwater vehicle executes the fixed-point hovering command, in order to achieve hovering in the slender fluid structure, the command speed is reduced to a low speed after reaching the command depth to maintain attitude balance. Since the low-cost propeller cannot maintain propeller rotation under the command of too low speed, a linear range is added to achieve the hovering requirement. The specific formulas are shown in Equations (18)-(19) below.

[0114]

[0115]

[0116] Among them, e h =hh d The depth difference is represented by m, the weight of the quadcopter unmanned underwater vehicle is represented by g, the acceleration due to gravity is represented by V, the displacement volume is represented by ρ, and the density of water is represented by k. pT Indicates the hover control gain, δ T Representing the linear interval, to achieve the hovering requirement, δ can be adjusted according to performance specifications. T To meet control accuracy requirements, under normal circumstances, δ T ∈[-0.5m,0.5m].

[0117] The following specific example further illustrates the method of the present invention:

[0118] The quadcopter unmanned underwater vehicle (UUV) is a lightweight, small-caliber UUV with a 124mm diameter, a length of 1.6m, and a weight of 16.8kg. Its small size and light weight make it highly convenient for transportation, deployment, and recovery. The quadcopter UUV system offers two communication modes: 4G / 5G and WiFi. In the 4G / 5G mode, communication is achieved through a three-way interaction between a mobile phone, a tablet control unit, and a cloud server. The mobile phone serves as the wireless terminal controller and wireless data transmission radio, while a tablet replaces the traditional shore-based control box as the quadcopter UUV's control system.

[0119] Before embarking on a navigation mission, the quadcopter unmanned underwater vehicle (UUV) performs a self-check. The electrical self-check involves powering on the UUV and emitting an audible warning; the servo motors rotate one revolution clockwise and then one revolution counterclockwise. The software self-check utilizes the mobile phone, the heart of the UUV, to monitor the onboard sensors by receiving commands from the tablet computer and observing the phone's display. The structural self-check involves deploying the UUV, adjusting its initial attitude in still water, checking for airtightness and other issues, and replacing any seals as needed.

[0120] Set the navigation mission and plan the flight path. Set the total flight time T. lim Limit depth h lim Lake and sea test mission area di lat di (i = 1, 2, 3, 4). Set the task type, plan the motion path, and set the motion mode and parameters for each segment of the path. The motion mode decomposition diagram is shown below. Figure 4 As shown, path 1: from the starting point, reach target point 1 underwater at a fixed depth, set the sailing speed or sailing time t1, and command the depth; path 2: from target point 1, reach target point 2 underwater at a fixed altitude, set the sailing speed or sailing time t2, and command the altitude; path 3: after reaching target point 2, hover in a fixed position for t3, set the hovering time, hovering altitude, and sailing speed; path 4: after completing the hovering task, rise vertically to the surface, and set the sailing speed; after checking the set task path, ensure that the running time satisfies equation (20), save the planning data, and issue the task. After the quadcopter unmanned underwater vehicle completes the planned path, it executes path 5: after completing the task and rising to the surface, return to the starting point with one key, and set the sailing speed; path 6: reach the vicinity of the control console, adjust the attitude remotely, and prepare for the next test task.

[0121] T d = t1 + t2 + t3 <T lim (20)

[0122] In navigation missions, the underwater latitude and longitude are obtained by using the GPS-recorded position of the quadcopter unmanned underwater vehicle (UUV) while it is on the water surface, and dead reckoning is performed based on the underwater movement path. The command heading angle (Yaw) is then obtained through attitude calculation. d During the movement, once the spacecraft exceeds a certain depth... lim Or timeout T lim or the super-task area lon di lat di When i = 1, 2, 3, 4, the vehicle immediately stops, surfaces, and waits for a return trip or remote control command.

[0123] During depth control, the sailing speed or sailing time t1 is set, and the commanded depth is substituted into equations (3)-(11). The vehicle calculates the commanded heading angle based on the latitude and longitude of the target point 1 through dead reckoning, and calculates the rotational speed input V of the quadcopter unmanned underwater vehicle. i (i = 1, 2, 3, 4) and rudder angle input d i (i=1,2,3,4), by adjusting the control parameters in the formula, the dynamic performance of the closed-loop system of the vehicle is improved, the speed and smoothness of the system response are enhanced, and the attitude control and depth control of the vehicle are realized.

[0124] During altitude control, the sailing speed or sailing time t2 is set, the commanded altitude, and the collected system output response h needs to be substituted into equation (12) for calculation. Then, the speed input and rudder angle input are obtained according to equations (3)-(11). When the servo motor rotation angle changes, an excessively large rudder angle will affect the control effect of the system, so it is limited. Among them, δ de =20°, δ dd =5°.

[0125] During stationary hovering control, the hovering time t3, hovering height, and sailing speed are set. The propeller is rotated 90°, and the servo rotation angle is fixed. The speed input is obtained according to equations (13)-(19). The dynamic change of motion is achieved by controlling the speed. When floating vertically, the propeller of the propeller reverses to make it move upward.

[0126] When performing a one-key return mission, the navigation straight-line mission is performed at low speed with the starting point or designated return point as the mission target point. When it arrives near the operation command station, it is controlled by remote control operation, as shown in Equations (1)-(2). It is controlled by controlling the rear propulsion system of the quadcopter unmanned underwater vehicle. Remote control commands for forward, backward, left turn, and right turn are issued through the remote control handle. Each command is executed for 5 seconds.

[0127] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A motion control algorithm for a quadcopter unmanned underwater vehicle, characterized in that: the quadcopter unmanned underwater vehicle includes four servo motors (1) inside the body, and four thrusters (3) are symmetrically arranged on both sides of the body of the unmanned underwater vehicle. The four thrusters (3) are respectively connected to the independently moving servo motors (1) through a transmission shaft (2). The servo motors (1) are fixed on the propulsion control section housing (4). The structural layout of the quadcopter unmanned underwater vehicle is as follows: the origin of the body coordinate system is at the buoyancy center of the unmanned underwater vehicle, the x-axis points to the head along the rotation center of the vehicle body, the y-axis is located in the longitudinal symmetry plane of the vehicle, perpendicular to the x-axis and pointing upwards, and the positive direction of the z-axis is determined by the right-hand rule. The control inputs for the quadcopter unmanned underwater vehicle are: the rotational speed of the four thrusters, the forward / reverse signal, and the tilt angle of the thruster plane relative to the horizontal plane of the vehicle body; The motion control algorithms include two main categories: horizontal motion control and pitch plane motion control. I. Horizontal Motion Control 1.1 Remote control of water surface Remote control of the surface uses only the two rear thrusters of the quadcopter unmanned underwater vehicle, and the command speed V of the thrusters is set to... Set the corresponding servo tilt angle d to a fixed value. This causes the tail of the quadcopter unmanned underwater vehicle to be completely submerged in the water, i.e. 1.2 Underwater navigation motion control The quadcopter unmanned underwater vehicle achieves attitude and position control by adjusting the rotation speed and tilt angle of its four thrusters. (1) Speed ​​distribution: in, Indicates the first The rotational speed command for the No. 1 thruster This indicates the desired rotational speed command; (2) Rudder angle distribution: in, Indicates the first Thruster tilt command Indicates a pair of front thrusters Axial position coordinates Indicates a pair of rear thrusters Axial position coordinates; Speed ​​distribution and rudder angle distribution , and Determined by the following calculation formula; in, This represents the difference between the instruction input and the actual output. These represent depth, roll angle, pitch angle, and yaw angle, respectively. Indicates the system's control gain; Indicates the attitude control reference value; Represents a linear interval; Indicates attitude angular velocity; This indicates a tilt adjustment command. These represent tilt angle distribution command and tilt angle differential command, respectively. This indicates a speed adjustment command; II. Tilting Plane Motion Control: 2.1 Ascent and Descent Motion Control During the ascent and descent motion control, the tilt angle of all four thrusters is at 90°, that is, perpendicular to the horizontal plane of the unmanned aerial vehicle (UAV), and the rotational speed of the four thrusters is... in, in, Indicates the control gain of the system. Indicates the lower limit of depth control; 2.2 Fixed-point hovering motion control The hovering motion control is executed under the premise of the ascent and descent motion control. When performing the hovering task, the motion control in section 2.1 ascent and descent will be used. Replace with the following: in, Indicates depth difference, This indicates the weight of a quadcopter unmanned underwater vehicle. Represents gravitational acceleration. Indicates the volume of water discharged. This indicates the density of water. Indicates hover control gain. It represents a linear interval.

2. The motion control algorithm for a quadcopter unmanned underwater vehicle according to claim 1, characterized in that: 。

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