Mine tunnel inspection unmanned aerial vehicle and positioning system based on laser radar and UWB ranging

Abstract

The application provides a mine tunnel inspection unmanned aerial vehicle and positioning system based on laser radar and UWB ranging, and relates to the technical field of mine tunnel unmanned aerial vehicle inspection.The application can adapt to the positioning of the unmanned aerial vehicle in the mine tunnel environment through 360 laser radar and UWB ranging, so that the unmanned aerial vehicle can fly safely in the mine tunnel environment where light is dim and dust spreads due to long-term closure, and can land accurately in the preset hangar when necessary, thereby solving the key problem of the autonomous inspection of the unmanned aerial vehicle in the mine tunnel and expanding the application scenario of the unmanned aerial vehicle system in the inspection task.The application obtains the position and attitude of the unmanned aerial vehicle in the launch inertial system through the laser radar, so as to provide feedback control for the position and speed control module, and obtains the distance between the unmanned aerial vehicle and the UWB base station, so as to obtain the approximate position of the unmanned aerial vehicle in the mine tunnel and the relative position relationship with the hangar, thereby realizing the preliminary positioning of the landing point of the unmanned aerial vehicle, and being beneficial to the accurate positioning and landing of the unmanned aerial vehicle in the preset hangar.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mine unmanned aerial vehicle inspection, and particularly relates to a mine inspection unmanned aerial vehicle based on laser radar and UWB ranging and a positioning system. BACKGROUND

[0002] With the development and improvement of unmanned aerial vehicle technology, its practical application range is wider and wider, and the task demand is more complex and diversified. The use scenarios of unmanned aerial vehicles are no longer limited to outdoor scenarios, and the use is no longer limited to agricultural activities, photography and other activities in outdoor environments. Considering the inspection of various indoor dangerous environments, unmanned aerial vehicles have more advantages than humans in such environments, so it is necessary to study how unmanned aerial vehicles can achieve autonomous inspection in such environments.

[0003] When an unmanned aerial vehicle performs a cooperative task, the task execution scenario and task requirements need to be determined. According to whether there is a global navigation satellite system, it can be divided into a usable outdoor wide environment and a GNSS-denied environment such as a subway tunnel or a mine, where the positioning signal is weak or there is no positioning signal. In this environment, in order to solve the problem of autonomous positioning of unmanned aerial vehicles, currently domestic and foreign methods based on depth vision are mostly used, or methods that use optical flow to obtain higher accuracy speed information and then position. However, the above two positioning methods are based on visual sensors, and cannot be used in subway tunnels or mines where the light is dim and the environment is closed all year round, causing dust to spread.

[0004] Based on this, the present application is proposed. SUMMARY

[0005] The purpose of the present application is to provide a mine inspection unmanned aerial vehicle based on laser radar and UWB ranging and a positioning system in a large-scale mine environment without changing the physical structure of the mine, so that the unmanned aerial vehicle can fly safely in the mine environment and achieve preliminary positioning of the landing point, which is beneficial to subsequent precise positioning and landing of the unmanned aerial vehicle in the preset hangar.

[0006] To achieve the above purpose, the present application provides the following technical solutions:

[0007] The application provides a mine tunnel inspection unmanned aerial vehicle positioning system based on a laser radar and UWB ranging in a first aspect.

[0008] The sensor group comprises a gyroscope, a magnetometer, an accelerometer, a downward-looking laser ranging radar and an optical flow sensor; the magnetometer obtains the heading information of the unmanned aerial vehicle, the gyroscope and the accelerometer data are fused to provide the attitude angle and three-axis acceleration information of the unmanned aerial vehicle, the downward-looking laser ranging radar obtains the height information of the unmanned aerial vehicle, and the optical flow sensor estimates the speed information in the horizontal plane of the unmanned aerial vehicle by running an optical flow algorithm combined with the height of the unmanned aerial vehicle.

[0009] The application provides an unmanned aerial vehicle system in a second aspect, which adopts the mine tunnel inspection unmanned aerial vehicle positioning system based on the laser radar and UWB ranging, and comprises an actuator for executing corresponding movement according to the movement control signal sent by the lower computer, a power module for supplying power to the upper computer, the lower computer, the sensor group and the actuator, the UWB tag is further used for receiving the task instruction and / or movement instruction sent by the UWB base station and sending the task instruction and / or movement instruction to the upper computer, the lower computer is further used for receiving the position control instruction from the upper computer, combining the final unmanned aerial vehicle position information to generate the movement control signal, and the upper computer is further used for combining the current flight task to generate the expected control instruction and transmitting the expected control instruction to the lower computer for execution.

[0010] Compared with the prior art, the above technical scheme has the following advantages:

[0011] The mine tunnel inspection unmanned aerial vehicle and positioning system based on the laser radar and UWB ranging is a real-time positioning system for a mine tunnel with deployed UWB base stations, and can adapt to the unmanned aerial vehicle positioning in the mine tunnel environment through the 360 laser radar and UWB ranging, so that the unmanned aerial vehicle can safely fly in the mine tunnel environment with dim light and perennial closure leading to dust spreading, and can accurately land in the preset hangar when necessary, thereby solving the key problem of the unmanned aerial vehicle self-inspection in the mine tunnel and expanding the application scenario of the unmanned aerial vehicle system in the inspection task.

[0012] The application obtains the position and attitude of the unmanned aerial vehicle in the launch inertial system through the laser radar, provides feedback control for the position and speed control module, obtains the distance between the UWB base station, obtains the approximate position of the unmanned aerial vehicle in the mine tunnel and the relative position relationship with the hangar, thereby realizing the preliminary positioning of the unmanned aerial vehicle to the landing point, being beneficial to subsequent accurate positioning of the unmanned aerial vehicle to the preset hangar, and enabling the unmanned aerial vehicle to complete charging, cleaning and data transmission and other functions in the hangar, and providing a basis for realizing autonomous and regular inspection of the unmanned aerial vehicle in the mine tunnel. BRIEF DESCRIPTION OF DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only a part of the embodiments of the present application, and all other drawings obtained by those skilled in the art without creative labor based on the provided drawings are within the protection scope of the present application.

[0014] Figure 1 The module block diagram of the mine tunnel inspection unmanned aerial vehicle system based on the laser radar and UWB ranging provided by a specific embodiment of the present application is provided.

[0015] Figure 2 The internal module and signal flow block diagram of the host computer, flight control board, 360 laser radar and UWB tag in the mine tunnel inspection unmanned aerial vehicle system based on the laser radar and UWB ranging provided by a specific embodiment of the present application.

[0016] The drawings are as follows: sensor group 1, gyroscope 11, magnetometer 12, accelerometer 13, downward-looking laser ranging radar 14, optical flow sensor 15, remote control receiver 16, lower computer 2, flight control board 21, pose fusion module 211, attitude control module 212, 360 laser radar 31, UWB tag 32, host computer 4, positioning and attitude determination module 41, obstacle avoidance centering module 42, speed control module 43, position control module 44, flight task module 45, flight state module 46, power supply module 5, battery 51, first DC-DC module 52, second DC-DC module 53, actuator 6, electronic speed controller 61, brushless motor 62, paddle 63, external safety guarantee module 7, remote controller 71. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0018] Embodiment One

[0019] Referring to Figure 1 The embodiment provides a mine tunnel inspection unmanned aerial vehicle positioning system based on a laser radar and UWB ranging, mainly composed of a sensor group 1, a lower computer 2, a 360 laser radar 31 (preferably a Wayfinder 360 laser radar 31), a UWB tag 32 and an upper computer 4. The embodiment also provides an unmanned aerial vehicle system, which adopts the mine tunnel inspection unmanned aerial vehicle positioning system based on the laser radar and UWB ranging, and mainly further includes an actuator 6 and a power module 5. In a preferred embodiment, the unmanned aerial vehicle system is also provided with an external safety guarantee module 7, that is, the unmanned aerial vehicle system mainly consists of the upper computer 4, the lower computer 2, the sensor group 1, the power module 5, the actuator 6 and the external safety guarantee module 7.

[0020] After the upper computer 4 receives the data of the Wayfinder 360 laser radar 31, the FAST-LIO algorithm is run to obtain the position and attitude of the unmanned aerial vehicle in the launch inertial system. The lower computer 2 receives the information and fuses the speed estimation information of the unmanned aerial vehicle and the pitch angle and roll angle attitude information provided by the sensor module to obtain more accurate unmanned aerial vehicle state quantities. The lower computer 2 transmits the state quantities of the unmanned aerial vehicle to the upper computer 4, combines the control requirements to solve the expected control quantities and transmits them to the lower computer 2 for execution. The actuator 6 provides power for the flight of the unmanned aerial vehicle. The power module 5 provides power support for the upper computer 4, the lower computer 2, the sensor group 1 and the actuator 6 and other airborne systems.

[0021] The upper computer 4, the lower computer 2 and the sensor group 1 in the embodiment will be described in detail below. The UWB tag 32 on the unmanned aerial vehicle can obtain the distance of different UWB base stations within the relative communication range by communicating with the self-deployed UWB base station, so as to obtain the position in the mine tunnel. At the same time, the UWB base station receives the instructions issued by the central control platform and sends them to the UWB tag 32, so as to change the current task of the unmanned aerial vehicle. Among them:

[0022] The sensor group 1 includes a plurality of sensors for acquiring preliminary state information of the UAV and sending to the lower computer 2. The sensor group 1 of the embodiment mainly consists of a gyroscope 11, a magnetometer 12, an accelerometer 13, a downward-looking laser ranging radar 14 and an optical flow sensor 15. More preferably, the sensors of the direct flight control used in the application according to application and performance requirements include a magnetometer 12, a gyroscope 11, a downward-looking laser ranging radar 14, an accelerometer 13 and a remote control receiver 16. Among them, the magnetometer 12, the gyroscope 11 and the accelerometer 13 are built-in integrated sensors of the flight control board 21. The magnetometer 12 provides the heading information of the system, and the data of the gyroscope 11 and the accelerometer 13 are fused to provide the attitude angle and three-axis acceleration information of the UAV system. The optical flow sensor 15 and the downward-looking laser ranging radar 14 are external sensors. The optical flow sensor 15 is a low-resolution downward camera, which can estimate the speed information of the UAV system in the horizontal plane by running the optical flow algorithm combined with the height of the UAV. The downward-looking laser ranging radar 14 can measure the accurate height information. The remote control receiver 16 and the remote controller 71 in the external safety guarantee module 7 are a set of signal receiving and sending equipment. By the pilot operating the control stick in the remote controller 71, the UAV can be forced to jump from the program control mode to the manual control mode, thereby ensuring the flight safety of the UAV system.

[0023] The lower computer 2 is built-in data fusion module, which is used for fusing the preliminary UAV position information obtained by a plurality of sensors to obtain accurate UAV position information and sending to the upper computer 4. The lower computer 2 is also used for receiving the position control instruction from the upper computer 4, combining the final UAV position information to generate the motion control signal. More preferably, according to the application and performance requirements, the PIXHAWK mini6 c is used as the lower computer 2, that is, the flight control board 21. The flight control board 21 runs the data fusion algorithm of the sensor, which fuses the data of the built-in sensors such as the magnetometer 12, the gyroscope 11 and the accelerometer 13, and the external sensors such as the optical flow sensor 15 and the downward-looking laser ranging radar 14 to obtain accurate position, speed, acceleration, attitude and other state information of the UAV system, and combines the control instruction received from the upper computer 4 with the state information to generate the PWM signal for controlling the motor speed. Then the PWM signal is transmitted to the electronic speed regulator 61 of the actuator 6 for controlling the speed of the brushless motor 62.

[0024] The upper computer 4 is used for receiving and processing information sent from the lower computer 2, the 360 laser radar 31 and the UWB tag 32, fusing to obtain the final unmanned aerial vehicle pose information, and generating a position control instruction. The upper computer 4 is also used to generate a desired control instruction in combination with the current flight task and deliver it to the lower computer 2 for execution. More preferably, the application uses NVIDIA Jetson TX2 NX as the upper computer 4 according to application and performance requirements. The upper computer 4 serves as a comprehensive module and has a state machine system running on the board. It receives information sent from the lower computer 2, UWB and other modules, generates a desired control instruction in combination with the current flight task, and delivers it to the flight control board 21 for execution. In the application, the control instruction is the desired attitude angle and the desired thrust of the unmanned aerial vehicle, on the basis of which the most flexible and safe control of the unmanned aerial vehicle system can be achieved.

[0025] External sensors, this part mainly includes the pathfinding 360 laser radar 31 and the UWB tag 32 directly connected to the upper computer 4. The pathfinding 360 laser radar 31 obtains IMU data and laser point cloud data and sends them to the upper computer 4. The pathfinding 360 laser radar 31 is a medium wavelength laser radar selected according to the mine environment, which has a certain penetration for dust inside the mine, thereby ensuring that the laser data is the distance of the real obstacle or wall. The laser radar can realize scanning in the horizontal direction of 360 degrees and the vertical direction of 59 degrees, so as to better scan the obstacle information in the three-dimensional space and send it to the upper computer 4 in the form of point cloud data. At the same time, the sensor itself has an IMU that can realize more accurate motion estimation. The UWB tag 32 is arranged on the unmanned aerial vehicle and is used for communication with the UWB base station already deployed in the mine to obtain the distance between the unmanned aerial vehicle and different UWB base stations, obtain the position information of the unmanned aerial vehicle in the mine and send it to the upper computer 4. The UWB tag 32 is also used to receive task instructions and / or motion instructions sent by the UWB base station and send them to the upper computer 4. The UWB tag 32 is a matching product of the original UWB base station in the mine and is generally used for position acquisition of miners or other underground equipment. In this embodiment, it is directly used on the unmanned aerial vehicle to calculate the approximate relative position of the unmanned aerial vehicle and the hangar. At the same time, the UWB tag 32 as a communication device can realize data transmission.

[0026] The actuator 6 is used to execute corresponding motion according to the motion control signal sent by the lower computer 2. More preferably, the actuator 6 includes an electronic speed regulator 61, four brushless motors 62 and four groups of blades 63. The electronic speed regulator 61 is used to control the rotating speed of the four brushless motors 62, and the four brushless motors 62 drive the four groups of blades 63 to rotate respectively.

[0027] Power module 5, for the host computer 4, lower computer 2, sensor group 1 and actuator 6 power supply. Power module 5 mainly includes battery 51, first DC-DC module 52 and second DC-DC module 53. Among them, the first DC-DC module 52 outputs 5V DC voltage, which provides power for the work of flight control board 21. The second DC-DC module 53 outputs 12V DC voltage, which provides voltage for the work of host computer.

[0028] Example two

[0029] Please refer to Figure 2 , the embodiment provides a kind of more preferably based on laser radar and UWB ranging mine tunnel inspection unmanned plane positioning system. Host computer 4 is built-in: positioning and pose module 41, for obtaining the position and attitude information of unmanned plane according to IMU data and point cloud data. Obstacle avoidance centering module 42, for generating obstacle avoidance centering instruction according to the point cloud data obtained. Speed control module 43, for generating corresponding speed control instruction according to obstacle avoidance centering instruction. Position control module 44, for generating position control instruction according to speed control instruction. Flight task module 45, for receiving task instruction and motion instruction from UWB tag 32 according to self-defined protocol, then instructs obstacle avoidance centering module 42 and / or flight state module 46. Flight state module 46, for generating corresponding flight state according to the instruction issued by flight task module 45, sends target state change to position control module 44;Position control module 44 adjusts position according to target state change, generates position control instruction.

[0030] Lower computer 2 is built-in: pose fusion module 211, for fusing the preliminary unmanned plane pose information obtained from multiple sensors with the position and attitude information of unmanned plane obtained in positioning and pose module 41 of host computer 4, to obtain final unmanned plane accurate position and attitude information, and send to host computer 4;Position control module 44 of host computer 4 generates position control instruction according to final unmanned plane accurate position and attitude information, and sends to attitude control module 212 of lower computer 2. Attitude control module 212, according to the position control instruction generated by position control module 44 in host computer 4, generates unmanned plane flight attitude control instruction and sends to actuator 6.

[0031] Each part module in example two transmits information in the way as shown in the accompanying Figure 2 , which guarantees the basic flight ability of unmanned plane and the interaction ability with outside world.

[0032] In a more preferred embodiment, the obstacle avoidance module employs an artificial potential field algorithm; FAST-LIO algorithm. The flight state module simulates and manages different flight states of the UAV and their state changes through a finite state machine. The pose fusion module employs an EKF2 UAV pose fusion algorithm. The attitude control module is achieved through a cascade PID control system.

[0033] FAST-LIO combines data from LiDAR (Light Detection and Ranging) and Inertial Measurement Unit (IMU) to achieve high-precision pose estimation through a tightly coupled Iterative Extended Kalman Filter (EKF). This algorithm performs well in fast motion, noisy, or cluttered environments, with high computational efficiency and robustness. Data fusion: FAST-LIO uses a tightly coupled EKF to fuse LiDAR feature points and IMU data. This filter can handle nonlinear systems and approximate the true state through iterative optimization. In the filter, LiDAR feature points and IMU data are jointly used to construct a residual function, and the state estimate is updated by minimizing the residual. Feature extraction: FAST-LIO extracts planar and edge features from LiDAR point clouds, which are used as observations in subsequent state estimation. Feature extraction is usually based on geometric properties such as local smoothness, and intensity information is also considered when extracting edge features. State estimation: Extracted feature points are used together with IMU integration results for point cloud matching to estimate relative pose. IMU data is used for integration to obtain a preliminary estimate of the relative pose, which helps maintain the stability of the algorithm in cases where LiDAR data is sparse or noisy. At the same time, the IMU integration result is also used for motion compensation of the LiDAR point cloud to eliminate distortion caused by sensor motion.

[0034] EKF2 (Extended Kalman Filter 2) is a state estimation algorithm widely used in the field of robots, drones, etc., especially in pose (position and attitude) estimation. EKF2 is a nonlinear version of the classic Kalman filter, suitable for handling nonlinear systems. It estimates the state of the system by linearizing the nonlinear system and using the system's state equation and observation equation. In pose fusion, EKF2 can fuse data from different sensors such as inertial measurement units (IMU), GPS, laser range finders, vision sensors, etc. to provide accurate position and attitude estimates.

[0035] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, but as long as the combinations of the technical features do not contradict, they should be considered within the scope of the present disclosure.

[0036] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A mine inspection UAV positioning system based on lidar and UWB ranging, characterized in that, include: The sensor array, comprising multiple sensors, is used to acquire preliminary status information of the UAV and send it to the lower-level device. The lower-level machine, with a built-in data fusion module, is used to fuse preliminary UAV pose information acquired from multiple sensors to obtain accurate UAV pose information, which is then sent to the upper-level machine. The lower-level machine includes: a pose fusion module, used to fuse the preliminary UAV pose information acquired from multiple sensors with the UAV position and attitude information obtained from the positioning and attitude determination module in the upper-level machine to obtain the final accurate UAV position and attitude information, which is then sent to the upper-level machine; the position control module of the upper-level machine generates position control commands based on the final accurate UAV position and attitude information and sends them to the attitude control module of the lower-level machine; the attitude control module generates UAV flight attitude control commands based on the position control commands generated by the position control module in the upper-level machine and sends them to the actuator. The 360 ​​LiDAR acquires IMU data and laser point cloud data and sends them to the host computer. The 360 ​​LiDAR is a medium-wavelength LiDAR selected according to the mine environment. It is used to scan obstacle information in three-dimensional space and send it to the host computer in the form of point cloud data. The 360 ​​LiDAR has a built-in IMU and acquires IMU data and sends it to the host computer. UWB tags are attached to drones to communicate with UWB base stations already deployed in the mine, obtain the distance between the drone and different UWB base stations, get the drone's location information in the mine, and send it to the host computer. The host computer is used to obtain the final UAV pose information and generate position control commands. The host computer includes: a positioning and attitude determination module for obtaining the UAV's position and attitude information based on IMU data and point cloud data; an obstacle avoidance and centering module for generating obstacle avoidance and centering commands based on the acquired point cloud data; a speed control module for generating corresponding speed control commands based on the obstacle avoidance and centering commands; a position control module for generating position control commands based on the speed control commands; a flight mission module for receiving mission commands and motion commands from UWB tags according to a custom protocol, and then issuing commands to the obstacle avoidance and centering module and / or the flight status module; a flight status module for generating corresponding flight statuses based on the commands issued by the flight mission module and sending target status changes to the position control module; and a position control module for adjusting its position based on target status changes and generating position control commands.

2. The mine inspection UAV positioning system based on lidar and UWB ranging according to claim 1, characterized in that, The sensor group includes a gyroscope, a magnetometer, an accelerometer, a look-down laser ranging radar, and an optical flow sensor. The magnetometer acquires the drone's nose orientation information, the gyroscope and accelerometer data are fused to provide the drone's attitude angle and three-axis acceleration information, the look-down laser ranging radar obtains the drone's altitude information, and the optical flow sensor runs an optical flow algorithm to estimate the drone's speed information in the horizontal plane based on the drone's altitude.

3. The mine inspection UAV positioning system based on lidar and UWB ranging according to claim 2, characterized in that, The lower-level machine uses a flight control board. The magnetometer, gyroscope, and accelerometer are integrated sensors built into the flight control board, while the downward-looking laser ranging radar and optical flow sensor are external sensors.

4. The mine inspection UAV positioning system based on lidar and UWB ranging according to claim 1, characterized in that, The obstacle avoidance and centering module adopts the artificial potential field algorithm and the FAST-LIO algorithm; the flight state module simulates and manages different flight states of the UAV and their state changes through a finite state machine; the pose fusion module adopts the EKF2 UAV pose fusion algorithm; and the attitude control module is implemented through a cascade PID control system.

5. A drone system, employing the mine inspection drone positioning system based on lidar and UWB ranging as described in any one of claims 1 to 4, characterized in that, include: An actuator is used to perform corresponding movements based on motion control signals sent by a lower-level machine. The power module is used to supply power to the host computer, slave computer, sensor group and actuator; the UWB tag is also used to receive task instructions and / or motion instructions sent by the UWB base station and send them to the host computer; the slave computer is also used to receive position control instructions from the host computer, and generate motion control signals by combining the final UAV pose information; the host computer is also used to generate the desired control instructions by combining the current flight mission and transmit them to the slave computer for execution.

6. The unmanned aerial vehicle system according to claim 5, characterized in that, The sensor group also includes a remote control receiver; the UAV system also includes an external security module, including a remote controller, for sending manual remote control commands to the remote control receiver; the remote control receiver receives the manual remote control commands and sends them to the lower-level machine.

7. The unmanned aerial vehicle system according to claim 5, characterized in that, The actuator includes an electronic speed controller, four brushless motors, and four sets of blades. The electronic speed controller controls the speed of the four brushless motors, which in turn drive the four sets of blades to rotate. The motion control signal generated by the lower-level computer is a PWM signal that controls the speed of the brushless motors. The PWM signal is transmitted to the electronic speed controller to control the speed of the brushless motors.

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