Amphibious unmanned aerial vehicle underwater three-dimensional point cloud scanning sonar detection system and method

Abstract

The invention discloses an amphibious unmanned aerial vehicle underwater three-dimensional point cloud scanning sonar detection system and method, an unmanned aerial vehicle adopts a water-air amphibious four-axis heavy-load unmanned aerial vehicle, a sonar detector adopts a three-dimensional point cloud scanning sonar, and specifically, the three-dimensional point cloud scanning sonar detection system adopts a three-dimensional point cloud scanning sonar detector. The water-air amphibious four-axis heavy-load unmanned aerial vehicle and the three-dimensional point cloud scanning sonar are organically integrated, the unmanned aerial vehicle takes off from a ground station, leaps to areas such as river banks where the unmanned aerial vehicle is difficult to pass and lands on the water surface, the three-dimensional point cloud scanning sonar is used for detecting the underwater terrain, and meanwhile when water flow with the large flow speed is encountered, the unmanned aerial vehicle can be used for detecting the underwater terrain. The flight system of the unmanned aerial vehicle is utilized to enable the unmanned aerial vehicle to hover on the water surface to resist water flow, so that the stability of the unmanned aerial vehicle is ensured, and the detection accuracy of underwater topography is improved. In addition, a Kalman filtering algorithm is adopted to filter data of the gyroscope and the accelerometer, real-time attitude information is obtained, the compensation amount of the attitude information is calculated, and safe take-off and landing of the unmanned aerial vehicle in a non-static state are achieved by compensating the rotating speed of the motor.

Description

Technical Field

[0001] The present invention belongs to the technical field of cross-domain detection, and in particular, relates to an underwater three-dimensional point cloud scanning sonar detection system and method for an amphibious unmanned aerial vehicle. Background Art

[0002] Traditional underwater topographic measurement methods have problems such as low efficiency, low accuracy, high cost, and great environmental impact. Traditional underwater topographic measurement methods are mainly based on unmanned platforms such as drones, unmanned ships, and underwater robots. However, due to factors such as complex measurement environments, changeable monitoring scenarios, and multiple types of hidden dangers in waters, the application of single unmanned platforms such as drones, unmanned ships, and underwater robots is limited. When unmanned ships conduct underwater topographic measurements, they need to be manually lifted into the water and back to land, which is time-consuming and labor-intensive. In addition, there are many landslides in the water area, and the river bank is difficult to approach, which poses a safety risk. UAVs can only use non-contact measurement of the surface of the water area, and the underwater target measurement accuracy is low. Underwater robots are limited by mobility and wireless communication, and are expensive. In addition, the complex and changeable embankment breach situation requires real-time breach monitoring and rapid scene construction with wide coverage, full elements, and high resolution capabilities. However, the existing breach monitoring technology has problems such as single perception, low resolution, and lack of underwater monitoring. The breach scene construction mostly uses two types of data sources based on video streams and geographic information, which is difficult to meet the needs of accurate breach monitoring, precise warning, and fine prevention and control. Therefore, there is a need for an amphibious unmanned aerial vehicle underwater three-dimensional point cloud scanning sonar detection system and method that has accurate detection results, is easy to operate, and has low cost. Summary of the invention

[0003] The purpose of the present invention is to provide an amphibious unmanned aerial vehicle underwater three-dimensional point cloud scanning sonar detection system and method with accurate detection results and timely detection. By organically integrating a water-air amphibious four-axis large-load unmanned aerial vehicle with a three-dimensional point cloud scanning sonar, the unmanned aerial vehicle takes off from a ground station, flies over difficult-to-pass areas such as river banks and lands on the water surface, and uses the three-dimensional point cloud scanning sonar to detect underwater terrain. At the same time, when encountering a large flow rate of water, the flight system of the unmanned aerial vehicle is used to make the unmanned aerial vehicle hover on the water surface to resist the water flow, thereby ensuring the stability of the unmanned aerial vehicle and improving the detection accuracy of the underwater terrain.

[0004] To achieve the above object, the present invention adopts the following technical solution: An underwater three-dimensional point cloud scanning sonar detection system for an amphibious unmanned aerial vehicle comprises an unmanned aerial vehicle, a ground station and a sonar detector, wherein the unmanned aerial vehicle comprises an airframe, a control system, a power system and an energy system, a mounting plate is arranged at the bottom of the unmanned aerial vehicle airframe, a frame is mounted on the mounting plate, left and right sides of the frame are provided with left-right symmetrical first and second water boots, a lifting mechanism connected to the frame is arranged between the first and second water boots, and the sonar detector is mounted on the lifting mechanism; The control system includes a main control chip, which is electrically connected to an attitude measurement module, an altitude measurement module, a positioning module, a wireless communication module, a crystal oscillator circuit, a reset circuit, a voltage detection circuit and an alarm circuit; the main control chip signal is connected to the power system, which includes a flight system and a navigation system. The flight system drives the flight of the UAV through four sets of rotors arranged on the fuselage, and the navigation system navigates through thrusters arranged on the first water boots and the second water boots.

[0005] The frame includes a front cross bar, a rear cross bar, a left vertical bar, a right vertical bar, a first oblique bar, a second oblique bar, a third oblique bar, a fourth oblique bar, a connecting cross bar, a lifting hydraulic cylinder and a rotating bracket. The front cross bar and the rear cross bar are arranged on the first water boot and the second water boot relative to each other front and back. The left ends of the front cross bar and the rear cross bar are connected to the first water boot, and the right ends of the front cross bar and the rear cross bar are connected to the second water boot. The left end of the front cross bar is penetrated with a first connecting block, the right end of the front cross bar is penetrated with a second connecting block, the left end of the rear cross bar is penetrated with a third connecting block on the same axis as the first connecting block, and the rear cross bar The right end of the left vertical rod is provided with a fourth connecting block on the same axis as the second connecting block, the front end of the left vertical rod passes through the first connecting block, the rear end of the left vertical rod passes through the third connecting block, the front end of the right vertical rod passes through the second connecting block, and the rear end of the right vertical rod passes through the fourth connecting block. The bottom end of the first oblique rod is connected to the front end of the left vertical rod, the bottom end of the second oblique rod is connected to the front end of the right vertical rod, the bottom end of the third oblique rod is connected to the rear end of the right vertical rod, and the bottom end of the fourth oblique rod is connected to the second rear end of the left vertical rod. The top ends of the first oblique rod, the second oblique rod, the third oblique rod and the fourth oblique rod are all connected to the machine body through a connecting plate. The left end of the connecting cross bar is arranged on the third oblique bar, the right end of the connecting cross bar is arranged on the fourth cross bar, the rear part of the rotating bracket is hinged on the rear cross bar, the lifting hydraulic cylinder is arranged on the connecting cross bar, the piston rod of the lifting hydraulic cylinder is connected to the front part of the rotating bracket, the sonar detector is installed at the front end of the rotating bracket, and the rear end of the rotating bracket is provided with an electronic control system for providing power and control for the sonar detector, and the electronic control system and the lifting hydraulic cylinder are both connected to the control system of the UAV.

[0006] The main control chip is connected to the energy system through a reserved port, and the energy system is electrically connected to the power system to provide power to the power system. The reserved ports include a USART port, an IIC port, an SPI port and an I / O port.

[0007] The sonar detector is a 3D point cloud scanning sonar with a built-in real-time surface sound velocity meter and high-precision inertial navigation positioning / attitude. The 3D point cloud scanning sonar is also configured with RTK, PPK or PPP. The 3D point cloud scanning sonar is used to obtain accurate and high-resolution ultra-wide strip water depth data and 3D / 2D images.

[0008] The 3DSS-iDX sonar detector uses Ping DSP™ for signal processing, which allows multiple incident angles to reach the detection area simultaneously for detection.

[0009] The detection method is implemented based on the above-mentioned amphibious drone underwater three-dimensional point cloud scanning sonar detection system, and includes the following steps: (1) The ground station sends a command to the drone, which flies over obstacles, lands on the water, and then sails on the water to the area to be tested. (2) The control system controls the lifting mechanism to lower the sonar detector to a specified depth underwater; (3) The drone navigates along a preset route and uses a sonar detector to draw an underwater topographic map; (4) The ground station monitors underwater terrain data and further controls the movement of the UAV based on the monitoring data; (5) After the underwater detection is completed, the control system controls the lifting mechanism to retract the sonar detector, and the UAV takes off from the water surface and returns to the ground station.

[0010] The specific operation process of step (2) is as follows: the lifting mechanism is controlled by the control system, the piston rod is extended, and the rotating bracket is pushed to rotate around the rear cross bar, so that the sonar detector is gradually extended underwater. After reaching the specified depth, the control system controls the lifting mechanism to stop extending the piston rod, and the lowering of the sonar detector is completed.

[0011] The specific operation process of step (3) is as follows: the sonar detector performs data processing and visualization, draws a three-dimensional image of the underwater terrain, and transmits the image data to the ground station through the control system.

[0012] In step (4), if the monitoring data of the ground station is affected by the water flow velocity, the flight system of the UAV is activated to make the UAV hover on the water surface to resist the water flow. After the UAV stabilizes, the sonar detector draws the underwater terrain map again.

[0013] The specific process of step (5) is as follows: the control system controls the piston rod of the lifting mechanism to retract and drive the rotating bracket to rotate in the opposite direction around the rear cross bar, so that the sonar detector gradually returns to its original position, and the UAV takes off and returns to the ground station.

[0014] The drone of this application adopts anti-disturbance control to solve the technical problem that the traditional controller cannot take off due to excessive vibration. The Kalman filter algorithm is used to filter the gyroscope and accelerometer data and obtain real-time attitude information, calculate the compensation amount of the attitude information, and compensate the motor speed to achieve safe take-off and landing of the drone in a non-static state.

[0015] The drone of the present application adopts a compass compensation algorithm for static interference of the navigation coordinate system, which solves the problem of the drone's heading confusion near iron components. The speed target value is generated by remote control operation, the speed feedback value of the GPS module is measured, and the controller calculates and generates the attitude angle control value and decomposes the attitude angle control value into the body coordinate system. The deviation between the speed direction information output by the GPS module and the heading angle direction measured by the magnetic compass is used for heading angle compass compensation to obtain an accurate heading angle, realize dynamic correction of magnetic declination and maintain the heading of the drone.

[0016] The drone of the present application adopts intelligent detection and fusion technology of sensor health to solve the problem of unbalanced altitude setting of barometer in quasi-confined space. It adopts dual IMU + sensor anomaly detection fusion algorithm, and uses the dual IMU built into the amphibious control system to detect and intelligently analyze the health of internal and external barometers, GPS, attitude and other sensor data in real time, and automatically selects the sensor with the highest health for fusion to obtain the difference between the minimized theoretical altitude compensation and the actual altitude compensation. By comparing the altitude data after minimizing the compensation with the altitude data in GPS, a difference threshold is given, and the final altitude information can be determined within the set threshold range, so that the drone can still stably set altitude when the internal air pressure is unbalanced.

[0017] The present invention organically integrates an amphibious four-axis large-load UAV with a three-dimensional point cloud scanning sonar. The UAV takes off from a ground station, flies over difficult-to-pass areas such as river banks, and lands on the water surface. The three-dimensional point cloud scanning sonar is used to detect underwater terrain. At the same time, when encountering a large flow rate of water, the UAV's flight system is used to make the UAV hover on the water surface to resist the water flow, thereby ensuring the stability of the UAV and improving the detection accuracy of the underwater terrain. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of the detection system of the present invention.

[0019] Figure 2 It is a structural schematic diagram of the frame of the present invention.

[0020] Figure 3 It is a flow chart of the detection method of the present invention.

[0021] Figure 4 Schematic diagram of the system of the UAV of the present invention.

[0022] Figure 5 It is a communication link diagram of the detection system of the present invention.

[0023] Figure 6 It is a data fusion attitude solution framework diagram of the control system of the present invention.

[0024] Figure 7 It is a flow chart of 3D point cloud scanning sonar data processing.

[0025] Figure 8 It is a working principle diagram of the detection system of the present invention. DETAILED DESCRIPTION

[0026] The embodiments of the present invention are further described below with reference to the accompanying drawings.

[0027] Embodiment 1 like Figure 1-8 As shown, an amphibious UAV underwater three-dimensional point cloud scanning sonar detection system includes a UAV, a ground station 1 and a sonar detector 25. The UAV includes a body 2, a control system, a power system and an energy system. A mounting plate is provided at the bottom of the UAV body 2, and a frame 3 is installed on the mounting plate. The left and right sides of the frame 3 are provided with left-right symmetrical first water boots 4 and second water boots 5. A lifting mechanism 8 connected to the frame 3 is provided between the first water boots 4 and the second water boots 5, and the sonar detector 25 is installed on the lifting mechanism 8; the first water boots 4 and the second water boots 5 adopt an NPL ship type design, which not only helps to reduce the wave-making resistance during the navigation of the UAV and improve the water sports performance of the UAV, but also optimizes the hydrodynamic performance of the UAV, so that the UAV can remain stable during high-speed navigation, reduce shaking and vibration, and improve the wave resistance and constant stability of the UAV. The first water boots 4 and the second water boots 5 are both quick-detachable structures and can be flexibly configured according to mission requirements. When the first water boots 4 and the second water boots 5 are removed, the UAV is a land-air UAV; when the first water boots 4 and the second water boots 5 are installed, the UAV is a water-air amphibious UAV. The control system includes a main control chip, which is electrically connected to a posture measurement module, an altitude measurement module, a positioning module, a wireless communication module, a crystal oscillator circuit, a reset circuit, a voltage detection circuit and an alarm circuit; the main control chip signal is connected to the power system, and the power system includes a flight system and a navigation system. The flight system drives the flight of the UAV through four sets of rotors 6 arranged on the body 2, and the navigation system navigates through the propellers 7 arranged on the first water boots 4 and the second water boots 5.

[0028] In addition, the specific parameters of the sonar detection system of the present application are as follows: model: quadcopter 6, material: carbon fiber fuselage, aluminum alloy connector, size: ≤3150mm*3000mm*700mm; maximum take-off weight of the system: ≥110kg; maximum flight time of the system: ≥50min; maximum flight speed of the system: ≥10m / s; maximum water navigation speed of the system: ≥5.0m / s; maximum flight altitude of the system: ≥500m; system communication distance: ≥2km (water surface), ≥10km (air); operating frequency: 450kHz; transmission waveform: CW, Broadband; 3D image coverage width: 8 to 14 times the water depth (sonar head to the bottom of the water), varying with the sound velocity profile and bottom type; maximum 3D range: 100m / single side; maximum resolution: 1.67 cm; depth coverage width: 8 to 16 times the water depth (sonar head to the bottom of the water) times, changing with the sound velocity profile, geometric structure and bottom type; maximum strip sounding range: 120m / single side; minimum sounding depth: 0.5m; maximum sounding depth: 75m (seawater); system maximum wind resistance level: 7; system protection level: IP54, core parts are waterproof and corrosion-resistant; has dual functions of drone and unmanned ship; excellent seismic performance, can adapt to the environment with large water surface fluctuations; survival sea condition reaches level 2, can sail on the water, moor on the water, take off and land on the water, and hover on the water.

[0029] The frame 3 includes a front cross bar 9, a rear cross bar 10, a left vertical bar 11, a right vertical bar 12, a first oblique bar 13, a second oblique bar 14, a third oblique bar 15, a fourth oblique bar 16, a connecting cross bar 17, a lifting hydraulic cylinder 18 and a rotating bracket 19. The front cross bar 9 and the rear cross bar 10 are relatively arranged on the first water boot 4 and the second water boot 5 front and back. The left ends of the front cross bar 9 and the rear cross bar 10 are connected to the first water boot 4, and the right ends of the front cross bar 9 and the rear cross bar 10 are connected to the second water boot 5. The left end of the front cross bar 9 is penetrated with a first connecting block 20, the right end of the front cross bar 9 is penetrated with a second connecting block 21, the left end of the rear cross bar 10 is penetrated with a third connecting block 22 on the same axis as the first connecting block 20, and the rear cross bar 1 0 is penetrated with a fourth connecting block 23 on the same axis as the second connecting block 21, the front end of the left vertical rod 11 passes through the first connecting block 20, the rear end of the left vertical rod 11 passes through the third connecting block 22, the front end of the right vertical rod 12 passes through the second connecting block 21, the rear end of the right vertical rod 12 passes through the fourth connecting block 23, the bottom end of the first oblique rod 13 is connected to the front end of the left vertical rod 11, the bottom end of the second oblique rod 14 is connected to the front end of the right vertical rod 12, the bottom end of the third oblique rod 15 is connected to the rear end of the right vertical rod 12, the bottom end of the fourth oblique rod 16 is connected to the two rear ends of the left vertical rod 11, and the top ends of the first oblique rod 13, the second oblique rod 14, the third oblique rod 15 and the fourth oblique rod 16 are all connected to the machine body 2 through the connecting plate 24; The left end of the connecting cross bar 17 is arranged on the third oblique bar 15, the right end of the connecting cross bar 17 is arranged on the fourth cross bar, the rear part of the rotating bracket 19 is hinged on the rear cross bar 10, the lifting hydraulic cylinder 18 is arranged on the connecting cross bar 17, the piston rod of the lifting hydraulic cylinder 18 is connected to the front part of the rotating bracket 19, the sonar detector 25 is installed at the front end of the rotating bracket 19, and the rear end of the rotating bracket 19 is provided with an electronic control system 26 for providing power and control for the sonar detector 25, and the electronic control system 26 and the lifting hydraulic cylinder 18 are both connected to the control system of the drone.

[0030] The main control chip is connected to the energy system through a reserved port, and the energy system is electrically connected to the power system to provide power to the power system. The reserved ports include a USART port, an IIC port, an SPI port and an I / O port.

[0031] The sonar detector 25 is a 3D point cloud scanning sonar with a built-in real-time surface velocity meter and high-precision inertial navigation positioning / attitude. The 3D point cloud scanning sonar is also equipped with RTK, PPK or PPP. The 3D point cloud scanning sonar is used to obtain accurate and high-resolution ultra-wide strip water depth data and 3D / 2D images. The best hydrographic topographic data and side scan image results can be obtained in shallow waters. At the same time, real-time 3D point cloud images are obtained, and the resolution of 2D side scan images is expanded to 3D point clouds and water depth data with 3D coordinates. The 3D software can display, capture and accurately measure the 3D dimensions of targets on the bottom or in the water body in real time, such as pipelines, cables, bridge piles, sunken ships, underwater structures or obstacles, biological habitats, and other targets that are difficult to find in water depth maps and 2D side scans.

[0032] The 3DSS-iDX of the Sonar Detector 25 uses Ping DSP™ for signal processing, and detects by simultaneously reaching the detection area (such as the seabed, sea surface, water column and multipath, etc.) through multiple incident angles. Combined with the signal processing technology of the 3DSS-iDX multi-beam echo sounder, it can obtain excellent resolution and water depth measurement accuracy within a swath width of more than 14 times the water depth.

[0033] This application can fly flexibly in the air and can quickly reach the designated mission waters for cruising, almost without being restricted by terrain and environment. It can take off and land from land, water or ships, and is not affected by water surface conditions, which greatly simplifies the equipment collection and release process. Especially when operating in remote waters, there is no need to send personnel to the site to release the ship, which greatly improves the efficiency of underwater terrain measurement and reduces the difficulty of deployment. This application uses three-dimensional point cloud scanning sonar technology to obtain high-resolution 3D images of the riverbed, and uses super-resolution processing technology to improve the details and clarity of the image, and then classify the riverbed bottom. This application uses underwater acoustic equipment such as multi-beam or side-scan sonar to emit sound waves and receive reflected signals, and generates 3D point cloud data of underwater terrain based on information such as the propagation time and intensity of the sound waves. The acquired 3D point cloud data is super-resolution processed, and the resolution and detail performance of the image are improved through methods such as algorithm optimization and interpolation, so that the texture and structure of the riverbed bottom are clearer. Based on the processed high-resolution 3D images, this application uses algorithms such as machine learning or deep learning to classify the riverbed bottom. According to the physical and chemical properties of the substrate, such as particle size, density, color, etc., the riverbed substrate is divided into different categories, such as sand, mud, rock, etc.

[0034] Embodiment 2 The detection method is implemented based on the above-mentioned amphibious drone underwater three-dimensional point cloud scanning sonar detection system. The use of three-dimensional point cloud scanning sonar to achieve underwater terrain measurement requires a series of processes such as data collection, processing, editing and mapping. The first is the collection of three-dimensional point cloud scanning sonar data, which requires the use of DGPS (differential global positioning system) or other high-precision positioning equipment to synchronize the position of the three-dimensional point cloud scanning sonar. The second is the processing of three-dimensional point cloud scanning sonar data. The original side-scan sonar data needs to be pre-processed by system correction, sound velocity correction, time delay correction, etc. to eliminate the influence of system errors and environmental factors. Then, the echo data is analyzed using three-dimensional point cloud scanning sonar bathymetry technology to extract the depth information of the underwater terrain. By splicing and mosaicking the side-scan sonar images, a side-scan sonar mosaic covering the entire survey area is generated. After obtaining the side-scan sonar mosaic and depth data, data editing and quality control are required. Through manual interactive editing, erroneous depth points are eliminated, and necessary interpolation and smoothing are performed. At the same time, the depth data is cross-checked and compared with external data to ensure the accuracy and reliability of the data. The last step is to make an underwater topographic map. The edited and checked depth data is imported into the mapping software to generate a DBM (digital water depth model). According to the measurement scale and mapping standards, the depth contours are generated, the terrain is rendered, and the annotations are marked, and finally the seabed topographic map that meets the requirements is output. The specific steps include the following: (1) Ground station 1 sends a command to the drone, which flies over the obstacle, lands on the water, and then sails on the water to the area to be tested. (2) The control system controls the lifting mechanism 8 to lower the sonar detector 25 to a specified depth underwater. The lifting mechanism 8 is controlled by the control system, and the piston rod extends, pushing the rotating bracket 19 to rotate around the rear cross bar 10, so that the sonar detector 25 is gradually extended underwater. After reaching the specified depth, the control system controls the lifting mechanism 8 to stop extending the piston rod, completing the lowering of the sonar detector 25.

[0035] (3) The UAV navigates according to the preset route and uses the sonar detector 25 to draw an underwater terrain map. The sonar detector 25 performs data processing and visualization, draws a three-dimensional image of the underwater terrain, and transmits the image data to the ground station 1 through the control system. The communication link of the UAV is designed as a 2.4G digital image transmission. The parameter data of the amphibious four-axis large-load UAV is read through the integrated board and transmitted back to the ground station 1 via the 2.4G digital image transmission. The three-dimensional point cloud scanning sonar has a large transmission bandwidth. The existing point-to-point digital transmission computer can only meet the transmission of up to 100 meters, but the actual operation scene is far beyond this distance. Therefore, the data of this device is generally processed on the UAV side through an industrial computer, and then shared to the ground side or the background command center through remote projection.

[0036] (4) The ground station 1 monitors the underwater terrain data and further controls the movement of the UAV based on the monitoring data. If the monitoring data of the ground station 1 is affected by the flow velocity of the water, the flight system of the UAV is activated to make the UAV hover on the water surface to resist the water flow. After the UAV stabilizes, the sonar detector 25 draws the underwater terrain map again. Figure 4 As shown in the figure, the attitude angle (pitch angle, roll angle, yaw angle) of the drone is calculated by attitude quaternion. Quaternion is a simple hypercomplex number, which is composed of real numbers plus imaginary units. Quaternion is a mathematical tool used to represent rotation in three-dimensional space, and its form is: q=(q0, q1, q2, q3) Where: q0 is the real part, representing the scalar part of the rotation; q1, q2, q3 are the imaginary parts, representing the vector part of the rotation. : The rotation of the drone around its own longitudinal axis (body x-axis); pitch angle : The rotation of the drone around its own horizontal axis (the y-axis of the body); yaw angle : The rotation of the drone around its own vertical axis (body z-axis).

[0037] (5) After the underwater detection is completed, the control system controls the lifting mechanism 8 to retract the sonar detector 25, and the UAV takes off from the water surface and returns to the ground station 1. The control system controls the piston rod of the lifting mechanism 8 to retract and drive the rotating bracket 19 to rotate in the opposite direction around the rear cross bar 10, so that the sonar detector 25 gradually returns to its original position, and the UAV takes off and returns to the ground station 1.

[0038] The control system of the present application adopts the self-disturbance rejection control technology to realize the safe take-off and landing function of the UAV under the state of non-static underlying surface; the anti-ferromagnetic interference technology is adopted to enable the UAV to realize the function of dynamically correcting the magnetic declination and maintaining the heading when the compass is unavailable; the sensor health intelligent detection fusion technology is adopted to realize the UAV's stable height setting function under the state of internal air pressure imbalance. By solving a series of key problems in the application of water-air amphibious four-axis large-load UAV in amphibious environment, the amphibious UAV has the ability to fly in the air, take off and land on water, sail on water, and operate on water. Specifically, the UAV of the present application adopts the self-disturbance rejection control to solve the technical problem that the traditional controller cannot take off due to excessive vibration. The Kalman filter algorithm is used to filter the gyroscope and accelerometer data and obtain real-time attitude information, calculate the compensation amount of the attitude information, and compensate the motor speed to realize the safe take-off and landing of the UAV in a non-static state. The UAV of the present application adopts the compass compensation algorithm of static interference of the navigation coordinate system to solve the problem of UAV heading confusion near iron components. The speed target value is generated by remote control operation, the speed feedback value of the GPS module is measured, and the controller calculates and generates the attitude angle control value and decomposes the attitude angle control value into the body 2 coordinate system. The deviation between the speed direction information output by the GPS module and the heading angle direction measured by the magnetic compass is used for heading angle compass compensation to obtain an accurate heading angle, realize dynamic correction of magnetic declination and maintain the heading of the drone. In addition, the drone of the present application adopts intelligent detection and fusion technology of sensor health to solve the problem of unbalanced height setting of barometer in quasi-confined space. The dual IMU+sensor anomaly detection fusion algorithm is adopted. The dual IMU built into the amphibious control system detects and intelligently analyzes the health of sensor data such as internal and external barometers, GPS, and attitude in real time, and automatically selects the sensor with the highest health for fusion to obtain the difference between the minimized theoretical height compensation and the actual height compensation. By comparing the height data after minimizing the compensation with the height data in GPS, a difference threshold is given, and the final height information can be determined within the set threshold range, so that the drone can still be stably set in the state of internal air pressure imbalance.

[0039] Specifically, the application conducts aerial flight, surface navigation, and underwater terrain measurement tests in a lake in Jiangbei New District, Nanjing. The test results show that the amphibious four-axis large-load UAV flies smoothly, sails quickly on the surface, turns smoothly, can sail stably according to the preset route, and the side-scan sonar supporting software can display the three-dimensional image of the underwater terrain in real time. In addition, the application conducted a practical teaching demonstration in the Madu River section of the Yellow River in Zhengzhou. The UAV took off from the top of the Madu Dam with a 3D underwater point cloud scanning sonar and landed smoothly in the river water under the dam. The amphibious UAV sailed on the water to the measurement area, and the 3D underwater point cloud scanning sonar immediately began to perform 3D digital scanning of the dam slope and bottom and the surrounding river sections. The water depth of the river channel is about 3.0 meters, the water depth of the bottom of the dam slope is about 4.9 meters, and the measurable dam height is up to 0.85 meters deep. The width of the scanning strip is about 50 meters at a time. During the scanning process, targets such as the wide-coverage underwater riverbed and dam slopes can be seen intuitively and clearly on the sonar screen in real time, and the position and water depth of each target point can be measured in real time. In summary, the present invention organically integrates the water-air amphibious four-axis large-load UAV with the three-dimensional point cloud scanning sonar. The UAV takes off from the ground station 1, flies over the river bank and other difficult-to-pass areas and lands on the water surface. The three-dimensional point cloud scanning sonar is used to detect underwater terrain. At the same time, when encountering a large flow rate, the UAV's flight system is used to make the UAV hover on the water surface to resist the water flow, ensure the stability of the UAV, and improve the detection accuracy of underwater terrain.

[0040] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. Amphibious UAV underwater three-dimensional point cloud scanning sonar detection system, characterized by: It includes a drone, a ground station and a sonar detector. The drone includes a body, a control system, a power system and an energy system. A mounting plate is provided at the bottom of the drone body, a rack is installed on the mounting plate, a left-right symmetrical first water boot and a second water boot are provided on the left and right sides of the rack, a lifting mechanism connected to the rack is provided between the first water boot and the second water boot, and the sonar detector is installed on the lifting mechanism; The control system includes a main control chip, which is electrically connected to an attitude measurement module, an altitude measurement module, a positioning module, a wireless communication module, a crystal oscillator circuit, a reset circuit, a voltage detection circuit and an alarm circuit; the main control chip signal is connected to the power system, which includes a flight system and a navigation system. The flight system drives the flight of the UAV through four sets of rotors arranged on the fuselage, and the navigation system navigates through thrusters arranged on the first water boots and the second water boots.

2. The underwater three-dimensional point cloud scanning sonar detection system for amphibious unmanned aerial vehicles according to claim 1 is characterized by: The frame includes a front cross bar, a rear cross bar, a left vertical bar, a right vertical bar, a first oblique bar, a second oblique bar, a third oblique bar, a fourth oblique bar, a connecting cross bar, a lifting hydraulic cylinder and a rotating bracket. The front cross bar and the rear cross bar are arranged on the first water boot and the second water boot relative to each other front and back. The left ends of the front cross bar and the rear cross bar are connected to the first water boot, and the right ends of the front cross bar and the rear cross bar are connected to the second water boot. The left end of the front cross bar is penetrated with a first connecting block, the right end of the front cross bar is penetrated with a second connecting block, the left end of the rear cross bar is penetrated with a third connecting block on the same axis as the first connecting block, and the rear cross bar The right end of the left vertical rod is provided with a fourth connecting block on the same axis as the second connecting block, the front end of the left vertical rod passes through the first connecting block, the rear end of the left vertical rod passes through the third connecting block, the front end of the right vertical rod passes through the second connecting block, and the rear end of the right vertical rod passes through the fourth connecting block. The bottom end of the first oblique rod is connected to the front end of the left vertical rod, the bottom end of the second oblique rod is connected to the front end of the right vertical rod, the bottom end of the third oblique rod is connected to the rear end of the right vertical rod, and the bottom end of the fourth oblique rod is connected to the second rear end of the left vertical rod. The top ends of the first oblique rod, the second oblique rod, the third oblique rod and the fourth oblique rod are all connected to the machine body through a connecting plate. The left end of the connecting cross bar is arranged on the third oblique bar, the right end of the connecting cross bar is arranged on the fourth cross bar, the rear part of the rotating bracket is hinged on the rear cross bar, the lifting hydraulic cylinder is arranged on the connecting cross bar, the piston rod of the lifting hydraulic cylinder is connected to the front part of the rotating bracket, the sonar detector is installed at the front end of the rotating bracket, and the rear end of the rotating bracket is provided with an electronic control system for providing power and control for the sonar detector, and the electronic control system and the lifting hydraulic cylinder are both connected to the control system of the UAV.

3. The underwater three-dimensional point cloud scanning sonar detection system for amphibious unmanned aerial vehicles according to claim 2 is characterized by: The main control chip is connected to the energy system through a reserved port, and the energy system is electrically connected to the power system to provide power to the power system. The reserved ports include a USART port, an IIC port, an SPI port and an I / O port.

4. The underwater three-dimensional point cloud scanning sonar detection system for amphibious unmanned aerial vehicles according to claim 3 is characterized by: The sonar detector is a 3D point cloud scanning sonar with a built-in real-time surface sound velocity meter and high-precision inertial navigation positioning / attitude. The 3D point cloud scanning sonar is also configured with RTK, PPK or PPP. The 3D point cloud scanning sonar is used to obtain accurate and high-resolution ultra-wide strip water depth data and 3D / 2D images.

5. The underwater three-dimensional point cloud scanning sonar detection system for amphibious unmanned aerial vehicles according to claim 4 is characterized in that: The 3DSS-iDX sonar detector uses Ping DSP™ for signal processing, which allows multiple incident angles to reach the detection area simultaneously for detection.

6. A detection method, implemented based on the underwater three-dimensional point cloud scanning sonar detection system of an amphibious unmanned aerial vehicle according to any one of claims 1 to 5, characterized in that: The steps include: (1) The ground station sends a command to the drone, which flies over obstacles, lands on the water, and then sails on the water to the area to be tested. (2) The control system controls the lifting mechanism to lower the sonar detector to a specified depth underwater; (3) The drone navigates along a preset route and uses a sonar detector to draw an underwater topographic map; (4) The ground station monitors underwater terrain data and further controls the movement of the UAV based on the monitoring data; (5) After the underwater detection is completed, the control system controls the lifting mechanism to retract the sonar detector, and the UAV takes off from the water surface and returns to the ground station.

7. The detection method according to claim 6, characterized in that: The specific operation process of step (2) is as follows: the lifting mechanism is controlled by the control system, the piston rod is extended, and the rotating bracket is pushed to rotate around the rear cross bar, so that the sonar detector is gradually extended underwater. After reaching the specified depth, the control system controls the lifting mechanism to stop extending the piston rod, and the lowering of the sonar detector is completed.

8. The detection method according to claim 7, characterized in that: The specific operation process of step (3) is as follows: the sonar detector performs data processing and visualization, draws a three-dimensional image of the underwater terrain, and transmits the image data to the ground station through the control system.

9. The detection method according to claim 8, characterized in that: In step (4), if the monitoring data of the ground station is affected by the water flow velocity, the flight system of the UAV is activated to make the UAV hover on the water surface to resist the water flow. After the UAV stabilizes, the sonar detector draws the underwater terrain map again.

10. The detection method according to claim 9, characterized in that: The specific process of step (5) is as follows: the control system controls the piston rod of the lifting mechanism to retract and drive the rotating bracket to rotate in the opposite direction around the rear cross bar, so that the sonar detector gradually returns to its original position, and the UAV takes off and returns to the ground station.

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