Four-rotor unmanned aerial vehicle based on underneath spherical laser radar

Abstract

The quad-rotor unmanned aerial vehicle comprises a vehicle body and a power system for driving the vehicle body to fly in the air, the spherical laser radar is arranged at the bottom of the vehicle body, the acting surface and the receiving surface of the spherical laser radar face downwards, and a sensor, a flight controller and a flight control upper computer are carried on the vehicle body. And the flight control upper computer is used for acquiring data acquired by the sensor and the spherical laser radar, and is also used for issuing a control instruction to the flight controller. Through the underlying spherical laser radar, unmanned aerial vehicle positioning in any complex unknown denial environment is realized, so that the quad-rotor unmanned aerial vehicle can cope with various unknown environments, and it is ensured that quad rotors can execute tasks under stable, accurate and safe flight conditions.

Description

Technical Field

[0001] The present invention relates to a drone, in particular to a quadrotor drone based on a downward spherical lidar. Background Art

[0002] As a subversive new equipment integrating "mechanization, informatization, and intelligence", drones have remarkable characteristics such as flexible combat use, high comprehensive combat efficiency, suitability for dangerous environments, low casualty rate, and low life-cycle cost. Among them, micro drones, due to their small size, low cost, rich procurement channels, and simple operation, can well perform tasks such as reconnaissance, harassment, and destruction in the battlefield, and have thus become a new focus of modern warfare. The micro drone system has higher mission coverage capabilities, stronger fault tolerance, and better battlefield flexibility and combat effectiveness, and is therefore widely used.

[0003] At present, drones mainly rely on the Global Navigation Satellite System (GNSS) for positioning, and the time-varying, dynamic, random, and adversarial nature of the war environment is very likely to cause the GNSS signal to be unavailable or unreliable. In addition, underground caves, deep buildings, dense jungles, and even cities with a high density of buildings are typical GNSS-denied environments. Therefore, simply relying on the Global Navigation Satellite System has become difficult to establish a reliable spatio-temporal reference and cannot meet the actual needs of future multi-scenario applications of drones. The ability to obtain high-precision, highly reliable, and autonomous spatio-temporal information in a satellite-denied environment has become an urgent need to promote the continuous development of drones. Therefore, developing a micro drone system in a denied environment has great practical significance for the multi-scenario application and intelligent development of drones.

[0004] With the improvement of navigation, data link and other technologies in a denied environment, the combat capability of unmanned systems in a denied environment is improved by developing collaborative algorithms and supervision technologies based on existing weapons. Multiple combat objectives such as virtual target strikes, threat response, and tactical formulation have been achieved, verifying the ability of the combat system to achieve test verification objectives when communications are interfered with and GPS signals are unavailable. In a denied combat environment, manned aircraft maintain radio silence as the lead aircraft, and unmanned aircraft enter the enemy's firepower strike range as wingmen to perform reconnaissance, detection and strike missions. Even in special war environments where GPS and local communications are strongly interfered with, the enemy's air defense system is strong, and there is electronic confrontation, the lead aircraft can remain hidden and perform high-risk tasks through the wingman, thereby effectively suppressing the enemy's defense system. Unmanned aircraft for underground mine detection and three-dimensional reconstruction are equipped with cameras and laser radars, which can collect data in mines. In response to the complex unknown environment and communication restrictions in mines, unmanned aircraft need to have autonomous detection and robust control capabilities to improve the accuracy of posture state estimation and achieve autonomous stable flight. They should also have the ability to reconstruct the surrounding environment to achieve autonomous obstacle avoidance. The safe use of drones in special denied spaces such as industrial buildings and pipelines can reduce equipment downtime, inspection costs and worker safety risks. It can also be used for indoor mapping to quickly digitize assets.

[0005] In the current research on micro-UAVs in denied environments, micro-quadcopters mainly rely on visual navigation technology and multi-source hybrid SLAM (Simultaneous Localization and Mapping) systems to achieve navigation and positioning. However, when faced with scenes with scarce feature points, such as large indoor warehouses or underground tunnels, it is difficult for the visual navigation system to extract a sufficient number of feature points for the system to accurately locate, which directly leads to insufficient positioning accuracy and affects the stable operation of the system. In contrast, multi-source hybrid SLAM navigation and positioning technology can better solve the problem of high-precision positioning in environments with scarce feature points. Among them, the SLAM solution of point cloud and vision fusion is one of the most widely used solutions. However, most current technical solutions tend to install solid-state laser radar (LiDAR) above the drone. This approach not only abandons the height determination function of the solid-state laser radar, but also forces the system to rely on other height determination sensors such as barometers, thus facing the dilemma of insufficient height determination accuracy or rising overall system costs. In addition, placing the solid-state lidar on top also reduces the density of point clouds collected by the drone in open scenes, further weakening the accuracy of positioning and limiting the flight altitude of the drone. Summary of the invention

[0006] Purpose of the invention: The purpose of the present invention is to provide a high-precision, highly stable and highly accurate quad-rotor drone based on a bottom-mounted spherical laser radar.

[0007] Technical solution: A quadrotor UAV based on a downward-mounted spherical lidar provided by the present invention includes a fuselage, a power system for driving the fuselage to fly in the air, a spherical lidar is arranged at the bottom of the fuselage, the working surface and the receiving surface of the spherical lidar face downward, a sensor, a flight controller and an upper flight control computer are carried on the fuselage, the upper flight control computer is used to obtain the data collected by the sensor and the spherical lidar, and is also used to send control instructions to the flight controller.

[0008] Further, the spherical lidar is connected to the fuselage through a radar mounting bracket, the radar mounting bracket includes a radar connecting plate, a frame connecting plate and a connecting soft rubber pad, the radar connecting plate is fixedly connected to the bottom of the fuselage, the frame connecting plate is fixedly connected to the mounting surface of the spherical lidar, the radar connecting plate and the frame connecting plate are connected through the connecting soft rubber pad, and the connecting soft rubber pad is used for shock absorption.

[0009] Further, the connecting soft rubber pad is cylindrical, the radar connecting plate and the frame connecting plate are connected through a plurality of cylindrical connecting soft rubber pads, and the upper bottom surface and the lower bottom surface of the cylindrical connecting soft rubber pad are respectively connected to the radar connecting plate and the frame connecting plate.

[0010] Further, it includes a leg group arranged below the fuselage, the leg group includes a plurality of legs, the legs extend outwards from the axis of the fuselage, and the legs form a 60-degree angle with the plane where the fuselage is located. The legs are used to avoid the visual blind area of the radar and provide a visual range and the height of the fuselage for the initial positioning of the radar.

[0011] Further, the fuselage has an upper, middle and lower layer plate structure, including an upper computer structure plate located in the upper layer, a power system structure plate located in the middle layer, and a power supply system and a sensing system structure plate located in the lower layer. The upper computer structure plate, the power system structure plate and the power supply system and the sensing system structure plate are fixedly connected through columns. The upper computer structure plate is used to install the flight controller and the upper flight control computer, the power system structure plate is used to install the power system, and the power supply system and the sensing system structure plate are used to install the power supply, the sensor and the spherical lidar.

[0012] Further, a plurality of receiving brackets are also fixed on the power supply system and the sensing system structure plate. The receiving brackets are respectively located on the front side, left side, right side and rear side of the fuselage. A downward-looking visible light sensor is installed on one or more receiving brackets. The visible light sensor includes a monocular pinhole camera, a binocular pinhole camera and a depth camera. The visible light sensor is used to identify ground feature targets.

[0013] Furthermore, the upper flight control computer uses an embedded computing device to provide computing functions. The upper flight control computer is connected to the spherical lidar at the bottom through an RJ45 network cable, connected to the visible light sensor through a USB data cable, and connected to the flight controller through a jumper group. The upper flight control computer integrates various sensors and schedules the flight controller to achieve target recognition and path planning.

[0014] Furthermore, the upper computer structure board, the power supply system and the sensing system structure board adopt lightweight, thin-walled and rigid materials, including carbon fiber and aluminum alloy. The power system structure board adopts lightweight, thick-walled and rigid materials, including carbon fiber and aluminum alloy. The flight controller is installed in a closed structure, and the closed structure adopts lightweight materials, including nylon and ABS plastic.

[0015] Beneficial effects: Compared with the prior art, the remarkable feature of the present invention is that through the downward spherical lidar, the positioning of the UAV in any complex unknown denial environment is realized, enabling the quadrotor UAV to cope with various unknown environments and ensuring that the quadrotor can perform tasks under stable, accurate and safe flight conditions; at the same time, the quadrotor UAV can be compatible with a variety of different task scenarios through modular design, and realizes a partially variable structure design for different task objectives; the system is simple, compact, lightweight, has strong environmental compatibility and task compatibility, and can adapt to different actual application requirements in various environments. In practical applications, the downward spherical lidar quadrotor UAV can be widely used in UAV area coverage search, specified target recognition, target three-dimensional reconstruction, building exterior detection, dangerous area survey, etc. in denial environments. For example, for the internal and external surface structures of high-risk buildings, using the downward spherical lidar quadrotor UAV for detection and reconstruction can reduce the risk of workers operating in unknown high-risk environments and improve the detection efficiency at the same time. Brief Description of the Drawings

[0016] Figure 1 is the overall structural schematic diagram of the quadrotor UAV based on the downward spherical lidar of the present invention;

[0017] Figure 2 is the working flow chart of the positioning and target recognition system in the present invention;

[0018] Figure 3 is the structural decomposition schematic diagram of the installation structure of the downward spherical lidar in the present invention;

[0019] Figure 4 is the structural decomposition schematic diagram of the three laminates of the airframe structure in the present invention. Detailed Embodiments

[0020] Such as Figure 1As shown in the figure, this embodiment provides a quadrotor UAV based on a downward-mounted spherical lidar, which includes a fuselage 1 for carrying a power system. The power system 8 is used to drive the fuselage 1 and the sensors mounted thereon to fly in the air. A mounting bracket 7 for a downward-looking camera at an optional position is mounted on the lower layer board of the fuselage 1. The downward-looking spherical lidar 3 and its bracket are mounted at the bottom of the fuselage 1 to jointly form the lidar mounting part and are controlled by flight control software. The flight control software is carried by a flight control host computer 10, is connected to the spherical lidar 3 through an RJ45 network cable, is connected to a visible light sensor through a USB data cable, and is connected to a bottom-layer flight controller 9 through a jumper wire to realize the issuance of control instructions and the acquisition of sensor data. Finally, all systems work in harmony to complete the control of the UAV.

[0021] As Figure 2 shown in the figure, the fuselage 1 has an upper, middle, and lower layer board structure, including an upper-layer host computer structure board 101, a middle-layer power system structure board 102, and a lower-layer power supply and sensing system structure board 103. The host computer structure board, the power system structure board, and the power supply and sensing system structure board are fixedly connected by columns. The host computer structure board is used to install the flight controller 9 and the flight control host computer 10, and at the same time provides a function of protecting the propellers. The power system structure board is used to install the power system 8. The power supply and sensing system structure board is used to install the power supply, sensors, and the spherical lidar 3.

[0022] The host computer structure board and the power supply and sensing system structure board are made of lightweight, thin-walled, and rigid materials, including carbon fiber and aluminum alloy. The power system structure board is made of lightweight, thick-walled, and rigid materials, including carbon fiber and aluminum alloy, which can provide sufficient structural strength while reducing the overall weight of the UAV. The flight controller 9 is installed in a closed structure, which is protected by the closed structure. The closed structure is made of lightweight materials, including nylon and ABS plastic, which can not only provide necessary waterproof and dustproof protection, but also provide structural support and reduce the weight of the UAV.

[0023] As Figure 3As shown, the spherical laser radar 3 is connected to the body 1 through the radar mounting bracket 2, and the active surface and receiving surface of the spherical laser radar 3 face downward. The radar active surface and the receiving surface face downward, so that the sensor can provide accurate position information, including horizontal position information and vertical height information. The initial height of the UAV is provided by the tripod assembly. The radar mounting bracket 2 includes a radar connecting plate 4, a frame connecting plate 5 and a connecting soft rubber pad 6. The radar connecting plate 4 is fixedly connected to the bottom of the body 1, and the frame connecting plate 5 is fixedly connected to the mounting surface of the spherical laser radar 3. The radar connecting plate 4 and the frame connecting plate 5 are connected by connecting soft rubber pads 6. The connecting soft rubber pads 6 are used for shock absorption, which converts the high-frequency vibration directly brought by the power system of the quadcopter UAV into a vibration with a relatively large amplitude but a relatively low frequency, thereby ensuring the information confidence of the IMU sensor built into the spherical laser radar. The connection soft rubber pad 6 is cylindrical, and the radar connection plate 4 and the frame connection plate 5 are connected by a plurality of cylindrical connection soft rubber pads 6, and the upper bottom surface and the lower bottom surface of the cylindrical connection soft rubber pad 6 are respectively connected to the radar connection plate 4 and the frame connection plate 5. In this embodiment, four connection soft rubber pads 6 are used, which are respectively arranged at the four corners of the radar connection plate 4. The frame connection plate 5 is also connected to an arc protection frame 12, and the two arc protection frames cross and surround the outside of the spherical laser radar to provide protection for the spherical laser radar.

[0024] A tripod group is arranged under the body 1, and the tripod group includes a plurality of tripods 11. The tripods 11 extend outward from the axis of the body 1, and the tripods 11 form an angle of 60 degrees with the plane where the body 2 is located, and the height provided is 25 cm. The tripods 11 are used to avoid the blind spot of the radar's field of view and provide the field of view range and body height for the initial positioning of the radar.

[0025] Several receiving brackets are also fixed on the structural plate of the power supply system and the sensor system. In this embodiment, four receiving brackets are provided, and the receiving brackets are respectively located on the front, left, right and rear sides of the body 1. One or more receiving brackets are installed with downward-looking visible light sensors, and the visible light sensors include but are not limited to monocular pinhole cameras, binocular pinhole cameras and depth cameras, etc. The visible light sensor is used to identify ground feature targets. It uses a USB data cable to connect to the flight control host computer and is controlled by the flight control host computer, and the recognition function is realized through software calls. The installation method of the visible light sensor can be changed to face the front of the drone body, and can be converted to an inspection task to perform functions such as identifying the exterior of the building and crack detection.

[0026] The upper flight control computer is used for calculation. It uses an embedded computing device to provide the computing function of relevant algorithms, especially a dedicated vision image processing edge computing embedded development board with graphic computing function and good floating-point computing ability, which is used to process the data transmitted back by the spherical lidar, visible light sensor, etc. At the same time, it can perform functions such as UAV control and path planning. The upper computer is connected to the spherical lidar at the bottom through an RJ45 network cable, connected to the visible light sensor at the lower part through a USB data cable, connected to the underlying flight controller through a jumper group, and realizes the functions of target recognition and path planning by integrating various sensors and scheduling the underlying flight controller.

[0027] As Figure 4 shown, the working process of the quadrotor UAV positioning and target recognition method based on the lower-mounted spherical lidar is as follows: The program starts with the startup environment. After the environment starts, the programs related to the underlying control and positioning functions are started in sequence. The underlying control will judge whether the positioning information is obtained. If the positioning information is not obtained, the program will not be able to proceed. If the positioning information is obtained, the data conversion function will be started, and further, the target recognition function and the trajectory planning function will be started simultaneously, and the UAV will be taken over to start executing the search program. When the program judges that the target is found, it will operate the UAV to fly to the target position, and the program ends.

Claims

1. A quadrotor UAV based on a downward-mounted spherical lidar, characterized in that, It includes a fuselage (1), a power system (8) that drives the fuselage (1) to fly in the air. A spherical lidar (3) is provided at the bottom of the fuselage (1), and the working surface and receiving surface of the spherical lidar (3) face downward. Sensors, a flight controller (9) and a flight control host computer (10) are carried on the fuselage (1). The flight control host computer (10) is used to obtain the data collected by the sensors and the spherical lidar (3), and is also used to send control instructions to the flight controller (9).

2. The quadrotor UAV based on the downward spherical lidar according to claim 1, characterized in that The spherical lidar (3) is connected to the fuselage (1) through a radar mounting bracket (2). The radar mounting bracket (2) includes a radar connecting plate (4), a frame connecting plate (5) and a connecting soft rubber pad (6). The radar connecting plate (4) is fixedly connected to the bottom of the fuselage (1), the frame connecting plate (5) is fixedly connected to the mounting surface of the spherical lidar (3), and the radar connecting plate (4) and the frame connecting plate (5) are connected through the connecting soft rubber pad (6). The connecting soft rubber pad (6) is used for shock absorption.

3. The quadrotor UAV based on the downward spherical lidar according to claim 2, characterized in that, The connecting soft rubber pad (6) is cylindrical. The radar connecting plate (4) and the frame connecting plate (5) are connected through a plurality of cylindrical connecting soft rubber pads (6). The upper bottom surface and the lower bottom surface of the cylindrical connecting soft rubber pad (6) are respectively connected to the radar connecting plate (4) and the frame connecting plate (5).

4. The quadrotor UAV based on the downward spherical lidar according to claim 1, characterized in that, It includes a tripod group arranged below the fuselage (1). The tripod group includes a plurality of tripods (11). The tripods (11) extend outward from the axis of the fuselage (1), and the tripods (11) form a 60-degree angle with the plane where the fuselage (2) is located. The tripods (11) are used to avoid the blind area of the radar's vision and provide a vision range and the height of the fuselage for the initial positioning of the radar.

5. The quadrotor UAV based on the downward spherical lidar according to claim 4, characterized in that, The fuselage (1) has an upper, middle and lower layer plate structure, including an upper computer structure plate located in the upper layer, a power system structure plate located in the middle layer, and a power supply system and sensing system structure plate located in the lower layer. The upper computer structure plate, the power system structure plate and the power supply system and sensing system structure plate are fixedly connected by columns. The upper computer structure plate is used to install the flight controller (9) and the flight control host computer (10). The power system structure plate is used to install the power system (8). The power supply system and sensing system structure plate is used to install the power supply, sensors and the spherical lidar (3).

6. The quadrotor UAV based on the lower spherical lidar according to claim 5, characterized in that, A number of receiving brackets are also fixed on the power supply system and sensing system structure plate. The receiving brackets are respectively located on the front side, left side, right side and rear side of the fuselage (1). One or more receiving brackets are installed with downward-looking visible light sensors. The visible light sensors include a monocular pinhole camera, a binocular pinhole camera and a depth camera. The visible light sensors are used to identify ground feature targets.

7. The quadrotor UAV based on the lower-mounted spherical lidar according to claim 6, wherein, The upper flight control computer (10) provides computing functions using an embedded-based computing device. The upper flight control computer (10) is connected to the spherical lidar (3) at the bottom through an RJ45 network cable, connected to the visible light sensor through a USB data cable, and connected to the flight controller (9) through a jumper group. The upper flight control computer (10) realizes target recognition and path planning by integrating various sensors and scheduling the flight controller.

8. The quadrotor UAV based on the downward spherical lidar according to claim 5, characterized in that The upper computer structure board, the power supply system, and the sensor system structure board are made of lightweight, thin-walled, and rigid materials, including carbon fiber and aluminum alloy.

9. The quadrotor UAV based on the lower spherical lidar according to claim 5, characterized in that, The power system structure board is made of lightweight, thick-walled, and rigid materials, including carbon fiber and aluminum alloy.

10. The quadrotor UAV based on the downward spherical lidar according to claim 1, characterized in that, The flight controller (9) is installed in a closed structure, and the closed structure is made of lightweight materials, including nylon and ABS plastic.

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