Ultrasonic direct-drive amphibious mobile robot and its drive method

Abstract

To disclose an ultrasonic direct drive type amphibious mobile robot and a driving method for the same.SOLUTION: An ultrasonic direct drive type amphibious mobile robot includes an underwater ultrasonic actuator 1 provided at a rear end part of a cabin 5, and a land ultrasonic actuator 2 provided at a bottom end part of the cabin 5. The mobile robot excites vibration in a primary telescopic mode in a thickness direction of a third vibrator by applying a drive voltage to the third vibrator of the underwater ultrasonic actuator 1, generates ultrasonic waves having same frequency in water, generates interaction thrust by ultrasonic waves and water, drives underwater travel of the amphibious mobile robot, applies a drive voltage to a first piezoelectric ceramic sheet and a second piezoelectric ceramic sheet of the land ultrasonic actuator 2 when travelling on a land, thereby exciting each vibration in primary flexural mode of a first vibrator and a second vibrator, and driving the land travel of the amphibious mobile robot.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to the technical field of amphibious mobile robots, and particularly to an ultrasonic direct drive type amphibious mobile robot and its driving method.

Background Art

[0002] Amphibious mobile robots have the ability to operate in different media of water and land, can achieve free movement between different media, and are widely applied in fields such as offshore environmental monitoring, environmental exploration, and unmanned reconnaissance. It has characteristics such as being able to move freely in water and on land due to its drivability in different media and being able to adapt to the complex environment of water / land. Furthermore, by endowing the amphibious mobile robot with the ability of remote control and navigation, risks can be reduced in an environment dangerous to humans, and the efficiency and safety of coastal operations can be improved. However, due to the driving principle, conventional amphibious mobile robots generate noise and bubbles in the water and the surrounding environment during underwater operations. In a delicate environment where silent operation is required, the noise and bubbles make the robot easier to be tracked, resulting in a decrease in concealment.

[0003] To meet the needs of various situations, several amphibious robots are currently under development. For example, Chinese patent document CN109017179A proposes an amphibious fire truck for firefighting applications, and Chinese patent document CN106394541A proposes an amphibious planing boat. Many conventional amphibious robots are designed based on drive systems such as propellers, wheelsets, and crawlers, and possess powerful characteristics such as high speed and high load capacity. However, it is clear that the output characteristics of propellers and wheelsets make amphibious robots based on this design prone to generating and tracking noise. When a propeller rotates, small bubbles are formed due to the combined action of the interaction between the blades and the water and the vibration of the blades. The pressure from the resulting bust changes can be converted into low-frequency sound waves, causing noise. In addition, tip vortices can be formed at the ends of the propeller blades, causing turbulence. In these turbulent and vorticous flows, gases in the water are mixed to form bubbles, and the turbulence itself also generates noise. These noises and bubbles that appear on the water surface, indicating the robot's operation, can be tracked, making it difficult for the robot to move or work in a concealed manner.

[0004] Regarding the power source for the propeller and wheelset, one method is to employ an internal combustion engine powered by gasoline or diesel. While this method offers superior power and adaptability to harsh environments, it has the drawbacks of high noise levels, environmental pollution, and a tendency to be easily detected, negatively impacting surveillance and making the robot more vulnerable when applied to fields such as environmental monitoring and unmanned reconnaissance. Another method is to employ a battery-powered motor. While this method reduces the noise of the amphibious robot's power source, it is difficult to completely eliminate the noise caused by the interaction between the propeller and water, leaving operational traces. Consequently, the high noise, high energy consumption, environmental interference, and ease of tracking of amphibious robots using conventional drive systems limit their applicability in fields such as reconnaissance.

[0005] As described above, conventional amphibious mobile robots employing propellers, wheelsets, and crawlers as drive systems have several drawbacks: they produce loud operating noise, leave obvious traces of operation, interfere with environmental exploration, and can easily detect the robot. Furthermore, using propellers as an underwater drive system makes it easy for bubbles to form at the rear, leading to high repair and maintenance costs due to propeller cavitation. In addition, when employing a multi-stage transmission structure linked to an internal combustion engine or motor, the multi-stage transmission from the energy source to the drive end results in significant energy loss, low conversion efficiency from propeller rotational power to forward power of the robot, and high power loss. Moreover, the drive structure itself is bulky and heavy. [Overview of the project]

[0006] To solve the above problems, the present invention proposes an ultrasonically driven amphibious mobile robot and a driving method thereof. By exciting the primary expansion and contraction mode in the thickness direction of the vibrating body of the underwater ultrasonic actuator and the primary deflection mode of the vibrating body of the land-based ultrasonic actuator, the robot is driven to move in water or on land, thereby solving problems such as the loud operating noise and obvious operating traces of conventional amphibious robots.

[0007] To achieve the above objectives, the present invention employs the following technical approach. In the first embodiment, the present invention includes a cabin, a drive control circuit provided inside the cabin, an underwater ultrasonic actuator provided at the rear end of the cabin, and a land-based ultrasonic actuator provided at the bottom end of the cabin, wherein both the underwater ultrasonic actuator and the land-based ultrasonic actuator are electrically connected to the drive control circuit. The aforementioned land-based ultrasonic actuator includes a first case and a first vibrator and a second vibrator provided on both sides of the first case, with a first piezoelectric ceramic sheet and a second piezoelectric ceramic sheet provided on the first vibrator and the second vibrator, respectively, and both the first piezoelectric ceramic sheet and the second piezoelectric ceramic sheet are electrically connected to a drive control circuit. The underwater ultrasonic actuator includes a second case and a third vibrating body provided within the second case. The aforementioned drive control circuit is used to drive the amphibious mobile robot to travel underwater by applying a drive voltage to the third vibrator, thereby exciting vibrations in the primary expansion / contraction mode in the thickness direction of the third vibrator, generating ultrasonic waves of the same frequency in water, and generating thrust through the interaction of ultrasonic waves and water. The aforementioned drive control circuit excites vibrations in the primary deflection mode of the first vibrator and the second vibrator, respectively, by applying a drive voltage to the first piezoelectric ceramic sheet and the second piezoelectric ceramic sheet, and is used to drive the amphibious mobile robot to travel on land, thereby providing an ultrasonic direct-drive amphibious mobile robot.

[0008] In an optional embodiment, underwater ultrasonic actuators are provided on both sides of the rear end of the cabin. By applying drive voltages of different magnitudes to the third vibrators of the two underwater ultrasonic actuators via a drive control circuit, and by applying drive voltages of different magnitudes to the first and second vibrators via the drive control circuit, acceleration, deceleration, and differential turning motion in water or on land are controlled in a differential manner.

[0009] As an optional embodiment, the motion direction of the amphibious mobile robot and the thrust of the underwater ultrasonic actuator and the land-based ultrasonic actuator are controlled in a closed loop. Specifically, this includes setting a target motion direction angle and a target thrust, collecting the current motion direction angle and actuator thrust, and feeding back the current motion direction angle and acceleration. It also includes obtaining an error angle from the target motion direction angle and the current motion direction angle, calculating the acceleration from the error angle using a direction PID controller, obtaining an error acceleration from the fed-back acceleration, and then feedback-controlling the thrust generated by the underwater ultrasonic actuator and the land-based ultrasonic actuator using a thrust PID controller.

[0010] In an optional embodiment, the cabin is further provided with a battery pack for outputting a power supply, the battery pack is connected to a drive control circuit, the drive control circuit converts the output of the power supply into a drive voltage and is used to apply it to the third vibrator, or the first piezoelectric ceramic sheet and the second piezoelectric ceramic sheet.

[0011] In an optional embodiment, the first piezoelectric ceramic sheet and the second piezoelectric ceramic sheet are provided with magnetic adsorption contacts, and the first piezoelectric ceramic sheet and the second piezoelectric ceramic sheet are electrically connected to the drive control circuit by the magnetic adsorption contacts.

[0012] In an optional embodiment, the third vibrating body is electrically connected to the drive control circuit by magnetic attraction contacts, and the third vibrating body is provided with a vibration-damping rubber ring.

[0013] As an optional embodiment, the third vibrating body is a piezoelectric ceramic that is both an excitation source and a vibrating body.

[0014] As an optional embodiment, the third vibrating body is a cylindrical sheet-shaped piezoelectric ceramic or an arc-shaped piezoelectric ceramic.

[0015] As an optional embodiment, the driving frequency band of the underwater ultrasonic actuator is a MHz-level frequency band, and the driving frequency band of the land-based ultrasonic actuator is a kHz-level frequency band.

[0016] In an optional embodiment, the land-based ultrasonic actuator further includes a fixed cover, with fixed rods provided at two nodes in the primary deflection mode of the first and second vibrators, the first case having a groove with an open upper end where the fixed rods are positioned, the groove forming a closed groove with the fixed cover, the fixed rods being tightly fitted with the first and second vibrators, and the fixed rods being gap-fitted with the first case and fixed cover.

[0017] In an optional embodiment, the drive control circuit is further used to receive control commands and select to enter a different operating mode according to the control command. The operating modes include an automatic mode, a water surface mode, and a land mode. In the different modes, a water level sensor detects whether the amphibious mobile robot is in water or not. If it is in water, the underwater ultrasonic actuator is activated; otherwise, the land ultrasonic actuator is activated. In the water surface mode, if the water level sensor detects that the amphibious mobile robot is not in water, a non-water surface error command is returned. In the land mode, if the water level sensor detects that the amphibious mobile robot is in water, a non-land error command is returned.

[0018] In a second embodiment, the present invention is The process involves applying a drive voltage to the third vibrator of an underwater ultrasonic actuator during underwater travel to excite vibrations in the primary expansion / contraction mode in the thickness direction of the third vibrator, generating ultrasonic waves of the same frequency in the water, generating thrust through interaction between the ultrasonic waves and water, and driving the underwater movement of the amphibious mobile robot. The present invention provides a method for driving an ultrasonically direct-driven amphibious mobile robot according to a first embodiment, which includes the step of applying a driving voltage to a first piezoelectric ceramic sheet and a second piezoelectric ceramic sheet of a land-use ultrasonic actuator during land travel to excite vibrations in the primary deflection mode of the first vibrator and the second vibrator, respectively, and thereby driving the land travel of the amphibious mobile robot.

[0019] The beneficial effects of the present invention compared to the prior art are as follows: This invention provides an ultrasonically driven amphibious mobile robot and a driving method thereof, which drives the robot's movement in water or on land by exciting the primary expansion / contraction mode in the thickness direction of the vibrating body of an underwater ultrasonic actuator and the primary deflection mode of the vibrating body of a land-based ultrasonic actuator. In a water medium, the high-frequency ultrasonic waves emitted by the underwater ultrasonic actuator propagate backward through the water medium and have strong directionality. The ultrasonic waves and water interact to generate an interactional thrust, which drives the robot's forward movement. During movement, the vibrating body of the underwater ultrasonic actuator does not undergo large mechanical displacement movements, and because the direction in which the ultrasonic waves apply thrust to the water flow is clear, no bubbles are generated in the water, the thrust is generated in a laminar flow, and no obvious traces are left on the water surface. Furthermore, because the ultrasonic waves form a sound field in the water using water as the medium, no ripples are formed on the water surface. On land, the frequency of the ultrasonic waves far exceeds the human audible frequency range, so there is no loud noise, only slight friction noise. This technology solves the problems of conventional amphibious robots, such as high operating noise and easily visible operating traces. It significantly reduces operating noise, enabling silent and traceless operation of amphibious robots, and has application potential in fields such as environmental monitoring and unmanned reconnaissance.

[0020] This invention employs a system that directly drives the system using ultrasound on land and water. When operating in water and on land, energy is converted into a flow such as electrical energy - vibration - sound waves - kinetic energy, with only a small amount of energy dissipated as heat energy. This prevents large energy losses, resulting in high energy conversion efficiency and low power loss.

[0021] The underwater and land-based ultrasonic actuators of the present invention exhibit extremely small mechanical displacements at the nm and μm levels, resulting in extremely low wear on the underwater ultrasonic actuator and the absence of bubble generation and cavitation. Furthermore, although the land-based ultrasonic actuator rubs against the ground, the vibrating body that contacts the ground is made of steel, resulting in a slow wear rate and lower repair and maintenance costs for the robot.

[0022] Advantages of additional aspects of the present invention will be provided in part in the following description, will become apparent in part from the following description, or will be understood by the practice of the present invention.

[0023] The drawings constituting a part of the present invention are for further understanding of the present invention, and the exemplary embodiments and the description thereof of the present invention are for interpreting the present invention and are not intended to unduly limit the present invention.

Brief Description of the Drawings

[0024] [Figure 1] It is a structural schematic diagram of an ultrasonic direct drive type amphibious mobile robot provided in Embodiment 1 of the present invention. [Figure 2] It is a structural schematic diagram of an underwater ultrasonic actuator provided in Embodiment 1 of the present invention. [Figure 3] It is a schematic diagram of the vibration mode of the piezoelectric ceramics of the underwater ultrasonic actuator provided in Embodiment 1 of the present invention. [Figure 4] It is a finite element simulation diagram of acoustic fluid coupling provided in Embodiment 1 of the present invention. [Figure 5] It is a structural schematic diagram of a land ultrasonic actuator provided in Embodiment 1 of the present invention. [Figure 6] It is a schematic diagram of the vibration mode of the vibrator of the land ultrasonic actuator provided in Embodiment 1 of the present invention. [Figure 7] It is a flowchart of closed-loop control for the movement direction and thrust of the robot provided in Embodiment 1 of the present invention. [Figure 8] It is a flowchart of the control policy of the robot provided in Embodiment 1 of the present invention.

Modes for Carrying Out the Invention

[0025] Hereinafter, the present invention will be further described in association with the drawings and embodiments.

[0026] It should be noted that the following detailed descriptions are all illustrative and intended to further illustrate the invention. Unless otherwise stated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the invention pertains.

[0027] It should be noted that the technical terms used herein are solely for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments of the present invention. As used herein, unless otherwise specified in the context, singular forms are intended to include plural forms, and the terms “include” and / or “contain” and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or apparatus comprising a series of steps or units may include, but is not limited to, any other steps or units not explicitly mentioned or specific to those processes, methods, products or apparatus.

[0028] Examples and technical features of the present invention may be combined with each other, as long as they do not contradict each other.

[0029] Example 1 This embodiment provides an ultrasonic direct-drive amphibious mobile robot, as shown in Figure 1, which includes a cabin 5, a drive control circuit 4 located inside the cabin 5, an underwater ultrasonic actuator 1 located at the rear end of the cabin 5, and a land-based ultrasonic actuator 2 located at the bottom end of the cabin 5, with both the underwater ultrasonic actuator 1 and the land-based ultrasonic actuator 2 being electrically connected to the drive control circuit 4. The aforementioned land-based ultrasonic actuator 2 includes a first case 28 and a first vibrator 21 and a second vibrator 24 provided on both sides of the first case 28, with a first piezoelectric ceramic sheet 22 and a second piezoelectric ceramic sheet 25 provided on the first vibrator 21 and the second vibrator 24, respectively, and both the first piezoelectric ceramic sheet 22 and the second piezoelectric ceramic sheet 25 being electrically connected to a drive control circuit 4. The underwater ultrasonic actuator 1 includes a second case 13 and a third vibrating body 11 provided inside the second case 13. The drive control circuit 4 is used to drive the amphibious mobile robot to travel underwater by applying a drive voltage to the third vibrator 11, thereby exciting vibrations in the primary expansion / contraction mode of the third vibrator 11 in the thickness direction, and simultaneously generating ultrasonic waves of the same frequency in the water, thereby generating thrust through the interaction of ultrasonic waves and water. The drive control circuit 4 is used to drive the amphibious mobile robot to travel on land by applying a drive voltage to the first piezoelectric ceramic sheet 22 and the second piezoelectric ceramic sheet 25, thereby exciting vibrations in the primary deflection mode of the first vibrator 21 and the second vibrator 24, respectively.

[0030] In this embodiment, underwater ultrasonic actuators 1 are provided on both sides of the rear end of the cabin 5 to provide thrust for underwater travel of the amphibious mobile robot. By adjusting the amplitude of the drive voltage applied to the third vibrator 11 of the two underwater ultrasonic actuators 1 by the drive control circuit 4, operations such as acceleration, deceleration, and differential turning are controlled.

[0031] Specifically, the amplitude of the drive voltage applied to the underwater ultrasonic actuator is controlled by an operational amplifier. As the drive voltage increases, the thrust provided by the underwater ultrasonic actuator increases. By supplying drive voltages of different magnitudes to the underwater ultrasonic actuators on both the left and right sides, differential movements such as acceleration, deceleration, and differential turning are achieved. Simultaneously, the robot's precise motion is achieved by closed-loop control of the direction of motion and the thrust generated by the underwater ultrasonic actuator using an acceleration sensor.

[0032] At the bottom of the cabin 5, there is a land-use ultrasonic actuator 2 to provide thrust for the amphibious mobile robot to travel on land.

[0033] Both the underwater ultrasonic actuator 1 and the land-based ultrasonic actuator 2 are connected to the cabin 5 by screws and are electrically connected to the drive control circuit 4 by waterproof cables and magnetic contacts.

[0034] The drive control circuit 4 includes a drive circuit board 41 and a main control circuit board 42. Of these, the drive circuit board is a high-voltage drive circuit board, and the purpose of the drive control circuit 4 employing a dual circuit board is as follows: 1) To separate high-voltage signals and low-voltage signals and avoid interference. 2) Because the space inside the robot is limited, the arrangement of a dual circuit board reduces the area of ​​the single circuit board, satisfying the design requirement of making the overall volume of the robot smaller and easier to achieve a compact structure.

[0035] The cabin 5 forms a sealed space with the magnetic adsorption canopy 6, and a battery pack 3 for outputting a predetermined power supply is further provided inside the cabin 5. The battery pack 3 is connected to a drive control circuit 4, which converts the output of the power supply into a drive voltage of a predetermined magnitude and frequency, and applies it to the third vibrator 11 of the underwater ultrasonic actuator 1 and the first piezoelectric ceramic sheet and second piezoelectric ceramic sheet of the land-based ultrasonic actuator 2, thereby exciting the vibrators of the underwater ultrasonic actuator 1 and the land-based ultrasonic actuator 2 and controlling the vibration mode of the vibrators.

[0036] In this embodiment, as shown in Figure 2, the underwater ultrasonic actuator 1 includes a second case 13, a sealing lid 14, and a third vibrator 11 provided in the internal space consisting of the second case 13 and the sealing lid 14. The third vibrator 11 is electrically connected to a drive control circuit 4, and a vibration-damping rubber ring 12 is provided on the third vibrator 11. Here, the third vibrator 11 is also a piezoelectric ceramic sheet, which functions as both an excitation source and a vibrator, and excites the primary expansion and contraction mode in the thickness direction of the piezoelectric ceramic sheet itself.

[0037] In addition to propellers, there are other new drive systems for amphibious mobile robots, such as traveling wave drive using flexible wave fins designed in Patent Document CN113771566A, jet drive using a piezoelectric pump driven by piezoelectric ceramics proposed in Patent Document CN113772053B, and drive using underwater thrust generated by a vibration and fluid-structure coupling method.

[0038] The amphibious mobile robot in this embodiment is similarly driven by a piezoelectric ceramic sheet. However, in this embodiment, high-frequency ultrasonic waves in the MHz frequency band are generated in the water using piezoelectric ceramics, and thrust is directly generated in the water based on the physical phenomenon that ultrasonic waves in this frequency band easily propagate from the actuator (solid) to the water (liquid). This is fundamentally different in principle from the driving method using fins and a pump described in the previous example.

[0039] In this embodiment, the third vibrating body 11 is a cylindrical sheet of piezoelectric ceramic, as shown in Figure 3, and operates in a primary expansion / contraction mode in the thickness direction with an operating frequency of 1.65 MHz. When an excitation voltage of the same frequency is applied to it, the piezoelectric ceramic vibrates in that mode and ultrasonic waves of the same frequency can be generated in the water. In this frequency band, the directivity of the ultrasonic waves is high, the thrust is strong, and a large thrust can be generated.

[0040] As one possible embodiment, the third vibrating body 11 may employ an arc-shaped piezoelectric ceramic to concentrate ultrasonic energy.

[0041] As shown in Figure 4, in this embodiment, an acoustic-fluid coupled simulation of underwater ultrasound in the frequency band is performed. The left figure is an image of the sound pressure level, showing that the sound pressure in the center is clearly higher than the sound pressure on both sides, indicating high directivity of the sound waves. The right figure is a fluid streamline image, showing that the sound waves in the frequency band generate a strong thrust on the water, creating a high-velocity water flow behind it, as well as generating two vortices.

[0042] In this embodiment, as shown in Figure 5, the land-based ultrasonic actuator 2 includes a first vibrator 21, a first piezoelectric ceramic sheet 22, a fixing rod 23, a second vibrator 24, a second piezoelectric ceramic sheet 25, a fixing cover 26, a magnetic adsorption contact 27, and a first case 28.

[0043] The bottom of the first case 28 is open, and the legs of the vibrating body directly contact the ground to achieve drive. A first vibrating body 21 and a second vibrating body 24 are provided on both sides of the first case 28. A first piezoelectric ceramic sheet 22 is provided on the first vibrating body 21, and a second piezoelectric ceramic sheet 25 is provided on the second vibrating body 24. The first vibrating body 21 and the second vibrating body 24 are used to drive the motion on both the left and right sides, respectively.

[0044] Magnetic contacts 27 are provided on the first piezoelectric ceramic sheet 22 and the second piezoelectric ceramic sheet 25, and the first piezoelectric ceramic sheet 22 and the second piezoelectric ceramic sheet 25 are electrically connected to the drive control circuit 4 by the magnetic contacts 27.

[0045] To ensure that vibrations from the first vibrating body 21 and the second vibrating body 24 are not transmitted to the first case 28, a fixing rod 23 is fixed to the two nodes of the first vibrating body 21 and the second vibrating body 24 in their primary deflection modes. The fixing rod 23 at one node penetrates both the first vibrating body 21 and the second vibrating body 24, ensuring that the linear displacement of the fixing rod 23 is extremely small, while maintaining a constant rotational displacement.

[0046] The first case 28 is provided with a groove at the upper end where the fixing rod 23 is positioned, and this groove forms a closed groove with part of the fixing lid 26. When assembled, the fixing rod 23 is tightly fitted with the first vibrating body 21 and the second vibrating body 24, and gap-fitted with the first case 28 and the fixing lid 26, providing rotational space for the fixing rod 23, greatly reducing the transmission of vibrations of the vibrating body to the case, and ensuring that the influence of external fixed boundary conditions on the vibration frequency of the primary deflection mode of the first vibrating body 21 and the second vibrating body 24 is also ensured.

[0047] In this embodiment, the land-based drive unit similarly employs an ultrasonic drive scheme, with a drive frequency band in the kHz range. The drive principle of the land-based ultrasonic actuator differs from that of the underwater ultrasonic actuator. In the underwater ultrasonic actuator, the piezoelectric ceramic functions as both an excitation source and a vibrator, exciting the primary expansion and contraction mode in the thickness direction of the piezoelectric ceramic itself. In contrast, in the land-based ultrasonic actuator, as shown in Figure 6, the piezoelectric ceramic sheet is thin and used only as an excitation source, applied to the excitation of the primary deflection mode of the steel first vibrator 21 and second vibrator 24, with a frequency of 48.5 kHz. In this mode, the direction of the landing of the legs that contact the ground generates the driving capability of the land-based ultrasonic actuator.

[0048] In this embodiment, by adjusting and controlling the drive voltage amplitude for the vibrating elements on both the left and right sides of the land-based ultrasonic actuator using the drive control circuit 4, the land-based ultrasonic actuator can achieve motions such as acceleration, deceleration, and differential rotation.

[0049] Specifically, the amplitude of the drive voltage applied to the land-based ultrasonic actuator is controlled by an operational amplifier. As the drive voltage increases, the thrust provided by the land-based ultrasonic actuator increases. By supplying drive voltages of different magnitudes to the vibrators on both the left and right sides, differential movements such as acceleration, deceleration, and differential turning are achieved. Simultaneously, the direction of motion and the thrust generated by the land-based ultrasonic actuator are controlled in a closed loop using an acceleration sensor, thereby achieving precise robotic motion.

[0050] In this embodiment, the closed-loop control flow for the robot's motion direction and thrust is as shown in Figure 7. Specifically, the target angle and target thrust are set, the current output angle and output thrust are collected by an acceleration sensor, the angle and linear acceleration are fed back, an error angle is obtained from the target angle and the fed-back angle, the acceleration is calculated from the error angle by the direction PID controller, an error acceleration is obtained from the fed-back acceleration, and then the thrust generated by the actuator is feedback-controlled by the thrust PID controller. Accurate control of the motion direction and thrust is achieved by a cascade PID control algorithm for direction and thrust.

[0051] In this embodiment, the drive control circuit integrates a wireless communication module for the robot. The wireless communication module receives control commands from the remote control handle, and as shown in Figure 8, upon receiving a command, it determines the command and selects a different operating mode. The operating modes include automatic mode, water surface mode, and land mode. In each mode, a water level sensor detects whether the robot is in water. If the robot is in water, the underwater ultrasonic actuator is activated; otherwise, the land ultrasonic actuator is activated. In water surface mode, if the water level sensor detects that the robot is not in water, a non-water surface error command is returned. In land mode, if the water level sensor detects that the robot is in water, a non-land error command is returned.

[0052] It is understood that the dimensions and shape of the vibrator and the number of piezoelectric ceramics in a land-based ultrasonic actuator may be changed, and other modes may be applied depending on the actual situation.

[0053] This embodiment provides an ultrasonically direct-driven amphibious mobile robot that interacts directly with two media, water and land, using an ultrasonic transducer, resulting in dimensions of 117.78 × 105.24 × 56.79 mm. 3A small prototype was constructed with a mass of 234.36g, employing a wireless communication system, capable of movement in both water and land, and possessing silent and traceless underwater maneuverability. The prototype achieved a maximum land speed of 154.66mm / s and a maximum underwater speed of 54.64mm / s, with a maximum bottom load of 1357.66g, which is 5.79 times its own weight. In addition, due to the unique advantages of being driven by an ultrasonic transducer, a minimum step distance of 6.5um can be achieved during land operation, enabling high-precision adjustment of position, attitude, and viewing angle in special reconnaissance environments.

[0054] Example 2 This embodiment provides a driving method for an ultrasonic direct-drive amphibious mobile robot as described in Embodiment 1. The process involves applying a drive voltage to the third vibrator of an underwater ultrasonic actuator during underwater travel to excite vibrations in the primary expansion / contraction mode in the thickness direction of the third vibrator, generating ultrasonic waves of the same frequency in the water, generating thrust through interaction between the ultrasonic waves and water, and driving the underwater movement of the amphibious mobile robot. The method includes the step of applying a drive voltage to the first piezoelectric ceramic sheet and the second piezoelectric ceramic sheet of a land-use ultrasonic actuator during land travel, thereby exciting vibrations in the primary deflection mode of the first vibrator and the second vibrator, respectively, and driving the land travel of the amphibious mobile robot.

[0055] The above has described specific embodiments of the present invention with reference to the drawings, but this does not limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications and variations that can be made based on the technical solutions of the present invention without requiring creative effort are also included within the scope of protection of the present invention. [Explanation of symbols]

[0056] 1. Underwater ultrasonic actuator 2. Ultrasonic actuators for land use 3 Battery pack 4. Drive control circuit 5 cabins 6 Magnetic Adsorption Canopy 11. Third Vibrating Body 12 Vibration-damping rubber rings 13. Case 2 14 Sealing lid 21 First vibrating body 22. First piezoelectric ceramic sheet 23 Fixed rod 24. Second Vibrating Body 25. Second piezoelectric ceramic sheet 26 Fixed lid 27 Magnetic adsorption contacts 28. Case 1 41 Drive circuit board 42. Main control circuit board.

Claims

1. The system includes a cabin, a drive control circuit located inside the cabin, an underwater ultrasonic actuator located at the rear end of the cabin, and a land-based ultrasonic actuator located at the bottom end of the cabin, with both the underwater and land-based ultrasonic actuators being electrically connected to the drive control circuit. The aforementioned land-based ultrasonic actuator includes a first case and a first vibrator and a second vibrator provided on both sides of the first case, the first vibrator and the second vibrator each being provided with a first piezoelectric ceramic sheet and a second piezoelectric ceramic sheet, and both the first piezoelectric ceramic sheet and the second piezoelectric ceramic sheet are electrically connected to a drive control circuit. The underwater ultrasonic actuator includes a second case and a third vibrating body provided within the second case. The aforementioned drive control circuit is used to drive the amphibious mobile robot to travel underwater by applying a drive voltage to the third vibrator, thereby exciting vibrations in the primary expansion / contraction mode in the thickness direction of the third vibrator, generating ultrasonic waves of the same frequency in water, and generating thrust through the interaction of ultrasonic waves and water. The drive control circuit is used to drive the amphibious mobile robot on land by applying a drive voltage to the first piezoelectric ceramic sheet and the second piezoelectric ceramic sheet, respectively, thereby exciting vibrations in the primary deflection mode of the first vibrator and the second vibrator, and is characterized in that it is used to drive the amphibious mobile robot on land.

2. An ultrasonic direct-drive amphibious mobile robot according to claim 1, characterized in that an underwater ultrasonic actuator is provided on both sides of the rear end of the cabin, and a drive control circuit applies drive voltages of different magnitudes to the third vibrators of the two underwater ultrasonic actuators, and a drive control circuit applies drive voltages of different magnitudes to the first vibrator and the second vibrator, thereby controlling acceleration / deceleration and differential turning motion in water or on land in a differential manner.

3. The ultrasonic direct-drive amphibious mobile robot according to claim 2, characterized in that the direction of motion of the amphibious mobile robot and the thrust of the underwater ultrasonic actuator and the land ultrasonic actuator are controlled in a closed loop, specifically by setting a target direction angle and target thrust, collecting the current direction angle and actuator thrust, and feeding back the current direction angle and acceleration; obtaining an error angle from the target direction angle and the current direction angle; calculating the acceleration from the error angle with a direction PID controller; obtaining an error acceleration from the fed-back acceleration; and then feedback-controlling the thrust generated by the underwater ultrasonic actuator and the land ultrasonic actuator with a thrust PID controller.

4. The ultrasonic direct-drive amphibious mobile robot according to claim 1, further comprising a battery pack for outputting power supply within the cabin, the battery pack being connected to a drive control circuit, the drive control circuit converting the output of the power supply into a drive voltage and applying it to a third vibrator, or a first piezoelectric ceramic sheet and a second piezoelectric ceramic sheet.

5. The first piezoelectric ceramic sheet and the second piezoelectric ceramic sheet are provided with magnetic adsorption contacts, and the first piezoelectric ceramic sheet and the second piezoelectric ceramic sheet are electrically connected to the drive control circuit by the magnetic adsorption contacts. The third vibrating body is electrically connected to the drive control circuit by magnetic attraction contacts, and the third vibrating body is provided with a vibration-damping rubber ring. The ultrasonic direct-drive amphibious mobile robot according to claim 1, characterized in that the third vibrating body is a piezoelectric ceramic that is both an excitation source and a vibrating body.

6. The ultrasonic direct-drive amphibious mobile robot according to claim 5, characterized in that the third vibrating body is a cylindrical sheet-shaped piezoelectric ceramic or an arc-shaped piezoelectric ceramic.

7. The driving frequency band of the aforementioned underwater ultrasonic actuator is a frequency band at the MHz level. The ultrasonic direct-drive amphibious mobile robot according to claim 1, characterized in that the drive frequency band of the aforementioned land-based ultrasonic actuator is a frequency band at the kHz level.

8. The ultrasonic direct-drive amphibious mobile robot according to claim 1, wherein the land-based ultrasonic actuator further includes a fixed cover, fixed rods are provided at two nodes in the primary deflection mode of the first vibrator and the second vibrator, the first case is provided with a groove with an open upper end where the fixed rods are placed, the groove forms a closed groove with the fixed cover, the fixed rods are tightly fitted with the first vibrator and the second vibrator, and the fixed rods are gap-fitted with the first case and the fixed cover.

9. The drive control circuit is further used to receive control commands and select to enter different operating modes according to the control commands, the operating modes include an automatic mode, a water surface mode and a land mode, and in each mode, a water level sensor detects whether the amphibious mobile robot is in water, if it is in water, the underwater ultrasonic actuator is activated, and if it is not, the land ultrasonic actuator is activated, and in the water surface mode, if the water level sensor detects that the amphibious mobile robot is not in water, a non-water surface error command is returned, and in the land mode, if the water level sensor detects that the amphibious mobile robot is in water, a non-land error command is returned, characterized in that an ultrasonic direct drive amphibious mobile robot according to claim 1.

10. The process involves applying a drive voltage to the third vibrator of an underwater ultrasonic actuator during underwater travel, thereby exciting vibrations in the primary expansion / contraction mode in the thickness direction of the third vibrator, generating ultrasonic waves of the same frequency in the water, generating thrust through interaction between the ultrasonic waves and water, and driving the underwater movement of the amphibious mobile robot. A method for driving an ultrasonic direct-drive amphibious mobile robot according to any one of claims 1 to 9, characterized by comprising the step of applying a drive voltage to a first piezoelectric ceramic sheet and a second piezoelectric ceramic sheet of a land-use ultrasonic actuator during land travel to excite vibrations in the primary deflection mode of the first vibrator and the second vibrator, respectively, and driving the land travel of the amphibious mobile robot.

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