An amphibious drone with a bionic water entry and exit design

Abstract

The present invention relates to the technical field of unmanned aerial vehicles (UAVs), and discloses an amphibious UAV with a bionic water entry and exit design, comprising a frame, four power assemblies, an underwater adjustment mechanism, a control system, and a power supply. The frame is provided with a front arm, a rear arm, and two side arms; the front power assembly is fixed to the end of the front arm, the rear power assembly is fixed to the end of the rear arm, and the two side power assemblies are rotatably mounted on the ends of the side arms; the axial directions of the first rotor mechanism and the first propeller mechanism of the front power assembly are both arranged along the Z direction; the rear power assembly and the two side power assemblies each include a second rotor mechanism and a second propeller mechanism, and the axial directions of the second rotor mechanism and the second propeller mechanism intersect; the underwater adjustment mechanism, the control system, and the power supply are all mounted on the frame, the underwater adjustment mechanism is transmission-connected to the two side power assemblies to drive the two side power assemblies to adjust their angles around the Y direction, and the control system and the power supply are electrically connected to the four power assemblies.

Description

Technical Field

[0001] The present invention relates to the technical field of unmanned aerial vehicles (UAVs), and in particular to an amphibious UAV with a bionic water entry and exit design. Background Art

[0002] Drones (UAVs) are unmanned aerial vehicles (UAVs) controlled by wireless remote control technology. Micro UAVs are widely used in urban security, agricultural production, aerial photography and mapping, and defense and military fields. UAVs typically fly only in the air and are unable to meet the requirements of cross-medium movement between water and air.

[0003] For example, a Chinese invention patent with authorization publication number CN107380423B and authorization publication date September 5, 2023, discloses an amphibious drone. Specifically, the drone includes a drone body with at least one arm, each arm having a drive component at the end. The upper end of the drive component is mounted with a rotor, and the lower end of the drive component is mounted with a marine propeller. The rotor and propeller are connected via a one-way bearing or a one-way clutch. When the drone is airborne, the rotor is driven to rotate, enabling the drone to fly normally in the air, and attitude adjustment is achieved by controlling the rotor. When the drone is in water, the rotor does not provide the efficiency required for underwater movement and does not operate. When the speed of the marine propeller is increased, the drone moves downward into the water, and the drone's attitude is then controlled to achieve underwater travel.

[0004] The current amphibious drone's operating process is as follows: when entering water from the air, the drone first lands smoothly and floats on the water surface, then switches to marine propeller operation to achieve entry and underwater travel. Similarly, when entering the air from the water, the drone floats on the surface due to buoyancy, and then controls the drone's rotors to fly out of the water.

[0005] However, when existing water-air amphibious drones perform cross-medium movement, they need to float on the water surface to switch power, and the entry and exit actions are discontinuous, resulting in low efficiency of water-air cross-medium movement. Summary of the Invention

[0006] The technical problem to be solved by the present invention is that when existing water-air amphibious drones perform cross-medium movement, they need to float and stay on the water surface to switch power, the entry and exit actions are discontinuous, and the water-air cross-medium movement efficiency is low.

[0007] In order to solve the above technical problems, the present invention provides an amphibious drone with a bionic water entry and exit design:

[0008] The amphibious drone with a bionic water entry and exit design includes a frame, four power components, an underwater adjustment mechanism, a control system, and a power supply. The frame has X-, Y-, and Z-directions, and is provided with a front arm and a rear arm extending along the X-direction, and two side arms extending along the Y-direction.

[0009] The four power assemblies are a front power assembly, a rear power assembly, and two side power assemblies. The front power assembly is fixedly mounted on the end of the front arm, the rear power assembly is fixedly mounted on the end of the rear arm, and the two side power assemblies are rotatably mounted on the ends of the corresponding side arms.

[0010] The front power assembly includes a first rotor mechanism and a first propeller mechanism, and the axis directions of the first rotor mechanism and the first propeller mechanism are both arranged along the Z direction; the rear power assembly and the two side power assemblies each include a second rotor mechanism and a second propeller mechanism, and the axis direction of the second rotor mechanism intersects with the axis direction of the second propeller mechanism;

[0011] The underwater adjustment mechanism, the control system and the power supply are all installed on the frame. The underwater adjustment mechanism is respectively connected to the two side power assemblies in a transmission manner to drive the two side power assemblies to adjust the angle around the Y direction. The control system and the power supply are respectively electrically connected to the four power assemblies.

[0012] Furthermore, the axial direction of the second rotor mechanism of the side power assembly is arranged perpendicular to the axial direction of the second propeller mechanism of the side power assembly.

[0013] Furthermore, a rotating seat is installed at the end of each of the two side arms, and the rotating seat is in the shape of a right angle. The second rotor mechanism of the side power assembly is arranged at one end of the rotating seat, and the second propeller mechanism of the side power assembly is arranged at the other end of the rotating seat.

[0014] Furthermore, a Y-direction through hole is opened inside the side arm, and a transmission shaft is rotatably installed in the Y-direction through hole, and one end of the transmission shaft is fixedly connected to the rotating seat; the underwater adjustment mechanism includes two servos, and the servos are connected to the other end of the corresponding transmission shaft for preventing rotation.

[0015] Furthermore, a steering gear disc is installed on the output shaft of the steering gear, a stepped shaft is fixed on the side of the steering gear disc facing away from the steering gear, and the stepped shaft is connected to the transmission shaft by belt transmission.

[0016] Furthermore, a fixing seat is provided at the end of the rear arm, and the shape of the fixing seat is a right angle. The second rotor mechanism of the rear power assembly is installed at the Z-direction end of the fixing seat, and the second propeller mechanism of the rear power assembly is installed at the X-direction end of the fixing seat.

[0017] Furthermore, the frame is also equipped with an electric adjustment component, which is electrically connected to the control system and the four power components respectively. The electric adjustment component is used to receive a control signal from the control system and adjust the speed of the power component according to the control signal.

[0018] Furthermore, an upper guard plate is provided between the front arm and the two side arms, and a lower guard plate is provided between the front arm and the lower part of the frame, and the lower surface of the lower guard plate is an arc-shaped surface; the lower part of the frame is fixedly connected to an outer frame, and the power supply is installed inside the outer frame.

[0019] Furthermore, the control system includes a task allocation module, a flight controller, an underwater motion controller and a switch, and the task allocation module is electrically connected to the switch;

[0020] The switching switch is electrically connected to the flight controller and the underwater motion controller respectively. The flight controller is used to control the operation of the rotor mechanism, and the underwater motion controller is used to control the operation of the propeller mechanism and the underwater adjustment mechanism.

[0021] Furthermore, a sensor assembly is also installed on the frame, which is used to detect the position, attitude and water depth of the amphibious drone in real time. The sensor assembly is electrically connected to the task allocation module to issue control instructions / mode switching instructions based on the position signal, attitude signal and water depth signal; the sensor assembly is electrically connected to the flight controller and the underwater motion controller to control the operation of the four power assemblies based on the position signal and attitude signal.

[0022] Compared with existing technologies, the present invention's amphibious drone with a bionic water entry and exit design offers the following advantages: The drone utilizes a frame, four power assemblies, an underwater adjustment mechanism, a control system, and a power supply. The frame includes a front arm and a rear arm extending in the X direction, as well as two side arms extending in the Y direction. The front power assembly is fixed to the end of the front arm, the rear power assembly is fixed to the end of the rear arm, and the two side power assemblies are rotatably mounted to the ends of the corresponding side arms. By distributing the four power assemblies frontally, leftward, and rightward relative to the frame and synchronously controlling their operation, the drone can achieve both aerial hovering and underwater travel.

[0023] The front power assembly includes a first rotor mechanism and a first propeller mechanism, with the axis of the first rotor mechanism arranged along the Z direction. The rear power assembly and both side power assemblies each include a second rotor mechanism and a second propeller mechanism. The first rotor mechanism of the front power assembly, the second rotor mechanism of the rear power assembly, and the second rotor mechanisms of the two side power assemblies are used to generate lift during flight. The two side power assemblies can adjust their angles in the Y direction, thereby changing the thrust angles of the two side power assemblies, allowing for flexible adjustment of the drone's flight attitude.

[0024] Accordingly, the first propeller mechanism of the front power assembly, the second propeller mechanism of the rear power assembly, and the second propeller mechanisms of the two side power assemblies are used to generate power for underwater travel. The axis of the first propeller mechanism is arranged along the Z direction, and the first propeller mechanism can cause the fuselage to twist underwater in the Y direction. Because the second propeller mechanisms of the two side power assemblies are vector propeller mechanisms, they can effectively prevent underwater rollover and overcome the instability of underwater movement. The underwater adjustment mechanism can drive the two side power assemblies to adjust their angles in the Y direction, allowing the second propeller mechanisms of the two side power assemblies to generate power within the X0Z plane.

[0025] Furthermore, when the second propeller mechanisms of the two side power assemblies are in opposite power states, the drone can twist around the Z direction underwater. Furthermore, the drone can be flipped 90 degrees from the X0Y plane to the XOZ plane. The second propeller mechanisms of the two side power assemblies are then adjusted to align with the axis of the first propeller mechanisms. These three propeller mechanisms can then be used to drive the drone in translational motion along the Y direction. Therefore, when the amphibious drone is submerged, the propeller mechanisms of the four power assemblies generate power in different directions, enabling translational motion in the X, Y, and Z directions, as well as twisting motion around the Y and Z directions, achieving five degrees of freedom in water.

[0026] When a drone enters the water from the air, it first adjusts its fuselage from level flight to a downward-slanting flight attitude, uses inertia to enter the water at an angle, shuts off the rotor mechanism, and simultaneously activates the propeller mechanism, allowing the drone to enter an underwater driving state. Accordingly, when a drone enters the air from the water, it first adjusts its fuselage to an upward-slanting driving attitude, uses the second propeller mechanism of the rear power assembly and the second propeller mechanisms of the two side power assemblies to generate underwater thrust, allowing the drone to fly out of the water in the manner of a manta ray. During the time it remains in the air after flying out of the water, the power mode is switched, the propeller mechanism is shut off, and the rotor mechanism is simultaneously activated, allowing the drone to enter an airborne flight state. Compared to existing drones that require them to float on the water to switch power, the bionic entry and exit design makes the entry and exit actions more seamless, and the water-to-air cross-medium motion efficiency is high.

[0027] In addition, if the drone floats on the water and needs to dive into the water, the first propeller mechanism of the front power assembly is first used to generate power to lift the head of the drone, ensuring that the rear half of the fuselage enters the water downward, and the second propeller mechanisms of the other three power assemblies are started to generate an upward oblique underwater thrust, causing the fuselage to briefly accelerate and rise out of the water, and have an initial velocity after staying in the air. Since the center of the drone is arranged at the front, it eventually dives into the water in an oblique downward manner under the action of inertia and gravity, achieving the purpose of the drone diving in a parabolic form. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 1 is a perspective schematic diagram of an amphibious UAV with a bionic water entry and exit design according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic front view of an amphibious drone with a bionic water entry and exit design according to an embodiment of the present invention;

[0030] Figure 3 1 is a schematic top view of an amphibious UAV with a bionic water entry and exit design according to an embodiment of the present invention;

[0031] Figure 4 This is a structural diagram of an amphibious UAV with a bionic water entry and exit design according to an embodiment of the present invention;

[0032] Figure 5 This is a diagram of the water entry action of an amphibious UAV with a bionic water entry and exit design according to an embodiment of the present invention;

[0033] Figure 6 This is a diagram of the amphibious drone with a bionic water entry and exit design according to an embodiment of the present invention, showing its water exit action;

[0034] Figure 7 This is a diagram of the diving action of the amphibious UAV with a bionic water entry and exit design according to an embodiment of the present invention;

[0035] Figure 8 This is a schematic diagram of a control system for an amphibious UAV with a bionic water entry and exit design according to an embodiment of the present invention;

[0036] Figure 9 This is a control logic diagram of an amphibious UAV with a bionic water entry and exit design according to an embodiment of the present invention;

[0037] Figure 10 This is a three-dimensional diagram of a mechanical comprehensive model of an amphibious UAV with a bionic water entry and exit design according to an embodiment of the present invention;

[0038] Figure 11 This is a front view of a comprehensive mechanical model of an amphibious UAV with a bionic water entry and exit design according to an embodiment of the present invention;

[0039] Figure 12 This is a plan view of a comprehensive mechanical model of an amphibious UAV with a bionic water entry and exit design according to an embodiment of the present invention;

[0040] In the figure, 1-frame, 11-front arm, 12-rear arm, 120-fixed seat, 13-side arm, 130-rotating seat, 131-Y-direction through hole, 14-outer frame, 15-upper guard plate, 16-lower guard plate, 2-power assembly, 21-front power assembly, 211-first rotor mechanism, 212-first propeller mechanism, 22-rear power assembly, 221-second rotor mechanism, 222-second propeller mechanism, 23-side power assembly, 3-underwater adjustment mechanism, 30-servo, 31-servo disk, 32-stepped shaft, 4-control system, 40-electric adjustment assembly, 5-power supply. DETAILED DESCRIPTION

[0041] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0042] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like used in the present invention to indicate the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0043] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0044] In the present invention, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; they may refer to direct connection or indirect connection through an intermediate medium; they may refer to internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0045] like Figures 1 to 7 As shown, an amphibious UAV with a bionic water entry and exit design according to an embodiment of the present invention includes a frame 1, four power assemblies 2, an underwater adjustment mechanism 3, a control system 4 and a power supply 5. The frame 1 has X, Y and Z directions, and is provided with a front arm 11 and a rear arm 12 extending along the X direction, and two side arms 13 extending along the Y direction; the four power assemblies 2 are a front power assembly 21, a rear power assembly 22 and two side power assemblies 23, the front power assembly 21 is fixedly mounted on the end of the front arm 11, the rear power assembly 22 is fixedly mounted on the end of the rear arm 12, and the two side power assemblies 23 are rotatably mounted on the ends of the corresponding side arms 13.

[0046] The front power assembly 21 includes a first rotor mechanism 211 and a first propeller mechanism 212, and the axial directions of the first rotor mechanism 211 and the first propeller mechanism 212 are both arranged along the Z direction; the rear power assembly 22 and the two side power assemblies 23 both include a second rotor mechanism 221 and a second propeller mechanism 222, and the axial direction of the second rotor mechanism 221 is arranged to intersect with the axial direction of the second propeller mechanism 222; the underwater adjustment mechanism 3, the control system 4 and the power supply 5 are all installed on the frame 1, and the underwater adjustment mechanism 3 is respectively connected to the two side power assemblies 23 to drive the two side power assemblies 23 to adjust the angle around the Y direction, and the control system 4 and the power supply 5 are respectively electrically connected to the four power assemblies 2.

[0047] This amphibious drone, featuring a biomimetic water entry and exit design, utilizes a chassis 1, four power assemblies 2, an underwater adjustment mechanism 3, a control system 4, and a power supply 5. The chassis 1 is equipped with a front arm 11 and a rear arm 12 extending in the X-direction, as well as two side arms 13 extending in the Y-direction. A front power assembly 21 is secured to the end of the front arm 11, a rear power assembly 22 is secured to the end of the rear arm 12, and two side power assemblies 23 are rotatably mounted to the ends of the corresponding side arms 13. By distributing the four power assemblies 2 frontally, leftward, and rightward relative to the chassis 1 and synchronously controlling their operation, the amphibious drone can achieve both aerial hovering and underwater travel.

[0048] The front power assembly 21 includes a first rotor mechanism 211 and a first propeller mechanism 212, with the axis of the first rotor mechanism 211 arranged along the Z direction. The rear power assembly 22 and the two side power assemblies 23 each include a second rotor mechanism 221 and a second propeller mechanism 222. The first rotor mechanism 211 of the front power assembly 21, the second rotor mechanism 221 of the rear power assembly 22, and the second rotor mechanisms 221 of the two side power assemblies 23 are used to generate lift during flight. The two side power assemblies 23 can be adjusted in the Y direction, thereby changing the thrust angle of the two side power assemblies 23, thereby enabling flexible adjustment of the drone's flight attitude.

[0049] Accordingly, the first propeller mechanism 212 of the front power assembly 21, the second propeller mechanism 222 of the rear power assembly 22, and the second propeller mechanisms 222 of the two side power assemblies 23 are used to generate power for underwater travel. The axis of the first propeller mechanism 212 is arranged along the Z direction, and the first propeller mechanism 212 can cause the fuselage to twist underwater in the Y direction. Because the second propeller mechanisms 222 of the two side power assemblies are vector propeller mechanisms, they can effectively prevent underwater rollover and overcome the instability of underwater movement. The underwater adjustment mechanism 3 can drive the two side power assemblies 23 to adjust their angles in the Y direction, allowing the second propeller mechanisms 222 of the two side power assemblies 23 to generate power within the X0Z plane.

[0050] Furthermore, when the second propeller mechanisms 222 of the two side power assemblies 23 are in opposite power states, the drone can twist about the Z direction underwater. Furthermore, the drone can be flipped 90 degrees from the X0Y plane to the XOZ plane. The second propeller mechanisms 222 of the two side power assemblies 23 are then adjusted to align with the axis of the first propeller mechanism 212. These three propeller mechanisms can then drive the drone to translate along the Y direction. Therefore, when the amphibious drone is submerged, the propeller mechanisms of the four power assemblies 2 generate power in different directions, enabling translational motion in the X, Y, and Z directions, as well as twisting about the Y and Z directions, thereby achieving five degrees of freedom in water.

[0051] If the drone enters the water from the air, Figure 5 As shown in the figure, first adjust the fuselage from level flight to a downward tilted flight attitude, use inertia to enter the water in an oblique manner, turn off the rotor mechanism and start the propeller mechanism at the same time, so that the drone enters the underwater driving state. Figure 6 As shown, the drone first adjusts the fuselage to an upward-angled driving posture. The second propeller mechanism 222 of the rear power assembly 22 and the second propeller mechanisms 222 of the two side power assemblies 23 generate underwater thrust, allowing the drone to emerge from the water similar to a manta ray. During the hovering time, the drone switches to a different power mode, shutting down the propeller mechanism and activating the rotor mechanism, allowing the drone to enter an airborne flight state. Compared to existing drones that require them to float on the water to switch power, the biomimetic entry and exit design allows for more seamless entry and exit, resulting in highly efficient water-to-air cross-medium motion.

[0052] In addition, if the drone is floating on the water and needs to dive into the water, Figure 7As shown, the first propeller mechanism 212 of the front power assembly 21 is first used to generate power to lift the head of the drone, ensuring that the rear half of the fuselage enters the water downward, and the second propeller mechanisms 222 of the other three power assemblies 2 are started to generate an oblique upward underwater thrust, so that the fuselage is briefly accelerated and rises out of the water, and has an initial velocity after staying in the air. Since the center of the drone is arranged at the front, it eventually penetrates into the water in an oblique downward manner under the action of inertia and gravity, thereby achieving the purpose of the drone diving in a parabolic form.

[0053] In this embodiment, the axial direction of the second rotor mechanism 221 of the side power assembly 23 is arranged perpendicular to the axial direction of the second propeller mechanism 222 of the side power assembly 23. Specifically, a rotating base 130 is mounted at the end of each of the two side arms 13. The rotating base 130 is in the shape of a right angle. The second rotor mechanism 221 of the side power assembly 23 is disposed at one end of the rotating base 130, and the second propeller mechanism 222 of the side power assembly 23 is disposed at the other end of the rotating base 130. When flying in the air, the axial direction of the second rotor mechanism 221 of the two side power assemblies 23 mainly remains in the Z direction. When traveling underwater, the propeller mechanisms 222 of the two side power assemblies 23 can adjust their angles within the X0Y plane, thereby achieving translational motion in the X and Z directions, as well as torsional motion around the X direction.

[0054] In addition, the side arm 13 has a Y-shaped through-hole 131 formed within it. A drive shaft is rotatably mounted within the Y-shaped through-hole 131, one end of which is fixedly connected to a rotating base 130. The underwater adjustment mechanism 3 includes two servos 30, each of which is fixedly connected to the other end of the corresponding drive shaft. A servo disc 31 is mounted on the output shaft of each servo 30. A stepped shaft 32 is fixed to the side of the servo disc 31 facing away from the servo 30. The stepped shaft 32 is connected to the drive shaft via a belt drive. The two servos 30 are mounted within the frame 1 via a fixing bracket and bolts. Each servo disc 31 is connected to a stepped shaft 32, each equipped with a driving pulley. A driven pulley is mounted on the corresponding end of the drive shaft. The belt drives the driving and driven pulleys. The two servos 30 drive the two drive shafts and the rotating base 130 on either side to rotate in the Y direction, thereby achieving angular control of the underwater propeller mechanism.

[0055] As a further preferred solution, a fixed seat 120 is provided at the end of the rear arm 12, and the shape of the fixed seat 120 is a right angle. The second rotor mechanism 221 of the rear power assembly 22 is installed at the Z-direction end of the fixed seat 120, and the second propeller mechanism 222 of the rear power assembly 22 is installed at the X-direction end of the fixed seat 120. The second propeller mechanism 222 of the rear power assembly 22 can generate a constant underwater thrust along the X-direction, ensuring that the drone has sufficient power for underwater translational movement.

[0056] In this embodiment, the frame 1 is also equipped with an electronic adjustment assembly 40, which is electrically connected to the control system 4 and the four power assemblies. The electronic adjustment assembly 40 receives control signals from the control system 4 and adjusts the rotational speed of the power assemblies accordingly. Furthermore, an upper guard plate 15 is provided between the front arm 11 and the two side arms 13, and a lower guard plate 16 is provided between the front arm 11 and the lower portion of the frame 1. The lower surface of the lower guard plate 16 is curved. The upper and lower guard plates 15 and 16 protect the drone's fuselage and internal components from damage caused by the impact of water entry, and also reduce the drag of the drone during underwater travel.

[0057] Frame 1 is manufactured using 3D printing technology. The arms are made of the high-strength Future 8500 high-toughness resin, while other components are made of the cost-effective Future 8200 resin. Frame 1 features reinforced ribs at stress-concentrating joints to prevent breakage. The lower portion of frame 1 is fixedly connected to an outer frame 14, within which the power supply 5 is mounted. This outer frame 14 serves as a buffer platform to prevent damage to the control system 4 and power supply 5 from severe vibrations during movement. Both the rotor and propeller mechanisms include waterproof motors, totaling eight in total, which drive the four sets of rotors and propellers, respectively. Each of the four rotor mechanisms is a foldable, two-bladed rotor, which minimizes air resistance and improves movement efficiency.

[0058] In addition, the control system 4 uses Pixhawk 2.4.8 with M8N GPS, and executes actions as required according to the instructions of the flight control computer. The control system 4 includes a task allocation module, a flight controller, an underwater motion controller, and a switch. Figure 8 As shown, the task allocation module is electrically connected to the switching switch; the switching switch is electrically connected to the flight controller and the underwater motion controller respectively. The flight controller is used to control the operation of the rotor mechanism, and the underwater motion controller is used to control the operation of the propeller mechanism and the underwater adjustment mechanism 3.

[0059] A sensor assembly is also installed on the frame 1, which is used to detect the position, attitude and water depth of the amphibious drone in real time. The sensor assembly is electrically connected to the task allocation module to issue control instructions / mode switching instructions based on the position signal, attitude signal and water depth signal; the sensor assembly is electrically connected to the flight controller and underwater motion controller to control the operation of the four power assemblies 2 based on the position signal and attitude signal.

[0060] It should be noted that during the water-to-air cross-medium movement, the drone uses its own sensor components to detect the fuselage position, speed, water pressure (or water depth) and other states in real time to determine whether it is currently in water, and then controls its entry into or exiting the water according to instructions. When underwater, the rotor mechanism is locked, and the propeller mechanism is used to control the underwater driving posture. When in the air, the propeller mechanism is locked, and the rotor mechanism is used to control the flight posture in the air.

[0061] Description of power control of amphibious drone:

[0062] Overview

[0063] When the drone is airborne, the underwater propellers are inoperative. By varying the throttle signal fed into the electronically controlled controller (ESC), the motor speed is adjusted, causing the rotors to rotate downward, generating thrust and counter-torque. As the throttle signal changes, the force and torque exerted by the rotors on the drone's center of mass change, thereby altering the acceleration and angular acceleration to control the drone's position and attitude.

[0064] When the drone is underwater, the rotors are inoperative. The motor speed can be adjusted by varying the throttle signal input to the electronically controlled regulator (ESR), and the servo angle can be adjusted by varying the PWM signal input to the servo. The underwater propellers, driven by the motors, generate thrust and counter-torque, which, in turn, changes the surface area of ​​thrust and torque under the servo drive. As the throttle and PWM signals change, the force and torque exerted by the propellers on the drone's center of mass change accordingly, thereby altering acceleration and angular acceleration to control the drone's position and attitude.

[0065] Amphibious UAV comprehensive model

[0066] The integrated model primarily includes the UAV's dynamics model in air and water, a control distribution model, and an electrical model. The dynamics model provides the mathematical relationship between control force and UAV motion, the control distribution model provides the mathematical relationship between control force and drive components, and the electrical model provides the mathematical model of the drive components. These models describe the relationship between the control inputs, such as the throttle signal and PWM signal, and the UAV's power.

[0067] · Symbol Description

[0068]

[0069]

[0070] Coordinate system

[0071] Reference Figures 10 to 12 The mechanical model orientation coordinates in

[0072] Mechanical comprehensive model

[0073] ●Basic physical quantities

[0074]

[0075] Kinematic equations

[0076]

[0077] Kinetic equations

[0078] Underwater environment

[0079] ◆Force equation

[0080]

[0081]

[0082] ◆Torque equation

[0083] ■Aerial environment

[0084] ◆Force equation

[0085]

[0086] ◆Torque equation

[0087]

[0088]

[0089] Control allocation model

[0090] The control distribution model is the inverse process of the control efficiency model. When we can obtain the desired thrust and torque through controller design, the control distribution model can help us further solve the required propeller speed.

[0091] Air flight mode

[0092] When the quadrotor is hovering in the absence of wind, its propeller pull and counter-torque can be expressed as

[0093]

[0094]

[0095] Among them, the constant c f and c M Can be determined by experiment.

[0096] The UAV is driven by four propellers during flight. The propeller speed determines the total thrust and torque of the quadcopter. For the "Ten" type UAV, the total thrust is

[0097]

[0098] The total control torque is

[0099]

[0100] This gives the control allocation model:

[0101]

[0102] Among them, u i (i=1,2,3,4) is the control instruction, and M ′ 4 is a reversible matrix, then the control allocation inverse model can be written as:

[0103]

[0104] Then normalize the speed signal to get the throttle signal:

[0105]

[0106] Underwater sports mode

[0107] The thrust and torque formulas for underwater propellers are as follows:

[0108]

[0109]

[0110] in,

[0111] T i and Q i Respectively represent the thrust and torque of the i-th propeller (the direction is opposite to the propeller angular velocity);

[0112] ρ represents the fluid density;

[0113] n i represents the rotation speed of the i-th propeller;

[0114] D p Indicates the underwater propeller diameter;

[0115] Thrust coefficient K T and torque coefficient K Q It can be obtained from the open water performance curve of this model of propeller.

[0116] Drones fly underwater i The vehicle is driven by four propellers (i = 1, 2, 3, 4). Propeller u1 generates downward thrust, forming a pitching moment; propellers u2, u3, and u4 generate forward thrust; and propellers u2 and u3 can rotate to generate longitudinal force components.

[0117] The pulling force on the drone is:

[0118]

[0119] The torque is:

[0120] To simplify the above model, we can assume that the two servos have the same and small rotation angles, that is, β1 = β2, and cosβ i ≈1,sinβ i ≈β i In addition, let the thrust in the direction of e2 be 0, then T z =0.

[0121] The control allocation matrix is:

[0122]

[0123] Among them, M4 is the control efficiency matrix. It can be seen that the control allocation inverse model is

[0124]

[0125] From Ty = 0, we can get Then update the M4 matrix.

[0126] The servo angle signal βi can be obtained as a PWM signal after inverse analysis of the servo model.

[0127] Then normalize the speed signal to get the throttle signal:

[0128]

[0129] · ESC model

[0130] The throttle command σ is an input signal of 0 to 1, and the battery voltage U b Is a given constant. The ESC receives the throttle command σ and the battery output voltage U b The equivalent average voltage is then generated

[0131] U m =σU b

[0132] Motor model

[0133] The ESC inputs the voltage signal to the motor, and the motor rotates to a stable speed. This relationship is approximately a linear relationship, that is,

[0134]

[0135] in, are all constants.

[0136] However, when we give a throttle command, the motor reaches a steady-state speed. It takes a certain amount of time to respond, which is called the dynamic response time of the motor, denoted as T m In general, engineers simplify the brushless DC motor into a first-order low-pass filter, whose transfer function is

[0137]

[0138] Therefore, the complete model of the brushless DC motor is

[0139]

[0140] Servo model

[0141] The simple electromechanical model of the servo (servo motor) can be represented by a linear second-order system, which converts the flight control's PWM (Pulse Width Modulation) signal into the servo's angular position.

[0142] First, the PWM signal is converted into a voltage signal:

[0143] V(t)=k pwm PWM(t)+V bias

[0144] where k pwm Is the proportional coefficient for converting PWM pulse width into voltage, V bias is the voltage bias, which we set to 0 here.

[0145] Then, the voltage signal V(t) passes through the servo motor driver and motor model, which can be described by the following second-order differential equation:

[0146]

[0147] Where β(t) is the angular position of the servo, J is the moment of inertia, b is the damping coefficient, k is the torsion spring stiffness, K t is the motor torque constant.

[0148] Convert the above formula into a transfer function model, and set the initial position and initial velocity to 0, and we can get:

[0149]

[0150] Water-air power switching

[0151] In terms of water-air control switching, we refer to a framework proposed by the Nezha Laboratory of Shanghai Jiao Tong University. The overall process of the control system is as follows: Figure 8 、 Figure 9 As shown in the figure, the task allocation module receives the drone's position measurement signal, analyzes the signal, and outputs a mode switch command or a general task command. After receiving the mode switch command, the switch sends the on / off signal command to the underwater operation controller and the flight controller, respectively. Furthermore, the control command issued by the controller is relayed by the switch unit before being output to the drone. The amphibious drone receives the control signal from the switch, while sensors and other components on the drone's body measure the drone's position and output this information to the controller. The drone receives the mode switch signal and the measurement information transmitted back by the body, and then outputs the control signal to the switch.

[0152] The task assignment module includes algorithms for switching between water and air modes. The Euler angles of the drone's body are calculated using the gyroscope, accelerometer, and magnetometer. The center of mass velocity and position are estimated based on the acceleration measurements. The processed water depth sensor data is then used to determine whether the drone has entered water. If the drone enters water, the task assignment module sends a mode switch command to the transfer switch, connecting the underwater motion controller and blocking the flight controller's signal.

[0153] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. An amphibious UAV with a bionic water entry and exit design, characterized by: The machine comprises a frame, four power assemblies, an underwater adjustment mechanism, a control system and a power supply. The frame has X, Y and Z directions, and is provided with a front arm and a rear arm extending along the X direction, and two side arms extending along the Y direction. The four power assemblies are a front power assembly, a rear power assembly, and two side power assemblies. The front power assembly is fixedly mounted on the end of the front arm, the rear power assembly is fixedly mounted on the end of the rear arm, and the two side power assemblies are rotatably mounted on the ends of the corresponding side arms. The front power assembly includes a first rotor mechanism and a first propeller mechanism, and the axis directions of the first rotor mechanism and the first propeller mechanism are both arranged along the Z direction; the rear power assembly and the two side power assemblies each include a second rotor mechanism and a second propeller mechanism, and the axis direction of the second rotor mechanism intersects with the axis direction of the second propeller mechanism; The underwater adjustment mechanism, the control system and the power supply are all installed on the frame. The underwater adjustment mechanism is respectively connected to the two side power assemblies in a transmission manner to drive the two side power assemblies to adjust the angle around the Y direction. The control system and the power supply are respectively electrically connected to the four power assemblies. The axial direction of the second rotor mechanism of the side power assembly is arranged perpendicular to the axial direction of the second propeller mechanism of the side power assembly; When the second propeller mechanisms of the two side power assemblies are in opposite power states, the fuselage is twisted around the Z direction underwater; and can drive the fuselage to flip 90 degrees from the X0Y plane to the XOZ plane, and then the second propeller mechanisms of the two side power assemblies are adjusted to be consistent with the axial direction of the first propeller mechanism. These three propeller mechanisms can be used to drive the drone to move horizontally along the Y direction.

2. The amphibious drone with a bionic water entry and exit design according to claim 1 is characterized in that: The ends of the two side arms are both equipped with a rotating seat, which is in the shape of a right angle. The second rotor mechanism of the side power assembly is arranged at one end of the rotating seat, and the second propeller mechanism of the side power assembly is arranged at the other end of the rotating seat.

3. The amphibious drone with bionic water entry and exit design according to claim 2 is characterized in that: A Y-direction through hole is provided inside the side arm, and a transmission shaft is rotatably installed in the Y-direction through hole, and one end of the transmission shaft is fixedly connected to the rotating seat; the underwater adjustment mechanism includes two servos, and the servos are fixedly connected to the other end of the corresponding transmission shaft.

4. The amphibious drone with a bionic water entry and exit design according to claim 3 is characterized in that: A steering gear disc is installed on the output shaft of the steering gear, a stepped shaft is fixed on the side of the steering gear disc facing away from the steering gear, and the stepped shaft is connected to the transmission shaft through a belt transmission.

5. The amphibious UAV with bionic water entry and exit design according to claim 1 is characterized in that: A fixing seat is provided at the end of the rear arm, and the shape of the fixing seat is a right angle. The second rotor mechanism of the rear power assembly is installed at the Z-direction end of the fixing seat, and the second propeller mechanism of the rear power assembly is installed at the X-direction end of the fixing seat.

6. The amphibious UAV with bionic water entry and exit design according to claim 1 is characterized in that: The frame is also equipped with an electric adjustment component, which is electrically connected to the control system and the four power components respectively. The electric adjustment component is used to receive a control signal from the control system and adjust the speed of the power component according to the control signal.

7. The amphibious UAV with bionic water entry and exit design according to claim 1 is characterized in that: An upper guard plate is provided between the front arm and the two side arms, and a lower guard plate is provided between the front arm and the lower part of the frame, and the lower surface of the lower guard plate is an arc-shaped surface; the lower part of the frame is fixedly connected to an outer frame, and the power supply is installed inside the outer frame.

8. The amphibious UAV with bionic water entry and exit design according to claim 1 is characterized in that: The control system includes a task allocation module, a flight controller, an underwater motion controller and a switch, wherein the task allocation module is electrically connected to the switch; The switching switch is electrically connected to the flight controller and the underwater motion controller respectively. The flight controller is used to control the operation of the rotor mechanism, and the underwater motion controller is used to control the operation of the propeller mechanism and the underwater adjustment mechanism.

9. The amphibious UAV with bionic water entry and exit design according to claim 8, characterized in that: A sensor assembly is also installed on the frame, which is used to detect the position, attitude and water depth of the amphibious drone in real time. The sensor assembly is electrically connected to the task allocation module to issue control instructions / mode switching instructions based on the position signal, attitude signal and water depth signal; the sensor assembly is electrically connected to the flight controller and the underwater motion controller to control the operation of the four power assemblies based on the position signal and attitude signal.

Images