Mine hole inspection unmanned aerial vehicle and positioning system based on laser radar and UWB distance measurement

Abstract

The invention provides a mine hole inspection unmanned aerial vehicle based on a laser radar and UWB distance measurement and a positioning system, and relates to the technical field of mine hole unmanned aerial vehicle inspection. Through the 360 laser radar and UWB distance measurement, the system can adapt to unmanned aerial vehicle positioning in the mine hole environment, so that the unmanned aerial vehicle can safely fly in the mine hole environment in which the light is dark and flying dust spreads due to the fact that the unmanned aerial vehicle is closed all the year round, the unmanned aerial vehicle is accurately positioned and lands in the preset hangar when necessary, the key problem that the unmanned aerial vehicle autonomously inspects in the mine hole is solved, and the unmanned aerial vehicle safety is improved. And the application scene of the unmanned aerial vehicle system under the inspection task is expanded. According to the invention, the position and attitude of the unmanned aerial vehicle under the launching inertial system are obtained through the laser radar for feedback control of the position and speed control module, and the distance between the unmanned aerial vehicle and the UWB base station is obtained to obtain the approximate position of the unmanned aerial vehicle in a mine and obtain the relative position relation with the hangar, so that the unmanned aerial vehicle can preliminarily position a landing point, and the unmanned aerial vehicle can be accurately located. And the subsequent unmanned aerial vehicle can be accurately positioned and landed in the preset hangar.

Description

Technical Field

[0001] The present invention relates to the technical field of mine inspection drones, and in particular to a mine inspection drone and a positioning system based on laser radar and UWB ranging. Background Art

[0002] With the development and improvement of drone technology, its actual application scope is getting wider and wider, and the mission requirements are becoming more complex and diversified. The use scenarios of drones are no longer limited to outdoor scenes, and their uses are no longer limited to agricultural, photography and other activities in outdoor environments. Considering the inspection of various indoor harsh environments, drones have more advantages than humans in such environments, so it is necessary to study how drones can achieve autonomous inspections in such environments.

[0003] When drones perform collaborative tasks, it is necessary to clarify the task execution scenario and task requirements. Depending on whether there is a global navigation satellite system, it can be divided into a wide outdoor environment that can be used and an unusable GNSS-denied environment, such as subway tunnels or mines 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 drones, currently domestic and foreign countries mostly use positioning methods based on deep vision, or use optical flow to obtain more accurate speed information and then locate. 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, resulting in the spread of dust.

[0004] The present invention is proposed based on this. Summary of the invention

[0005] The purpose of the present invention is to provide a mine inspection drone and positioning system based on lidar and UWB ranging, for the existing large-scale mine environment, without changing the physical structure of the mine, so that the drone can fly safely in the mine environment and achieve preliminary positioning of the landing point by the drone, which is conducive to the subsequent precise positioning of the drone and landing in the preset hangar.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a mine inspection drone positioning system based on laser radar and UWB ranging, comprising: a sensor group, comprising a plurality of sensors, for obtaining preliminary status information of the drone and sending it to a lower computer; a lower computer, with a built-in data fusion module, for fusing preliminary drone posture information obtained by a plurality of sensors to obtain accurate drone posture information and send it to a host computer; a 360 laser radar, for obtaining IMU data and laser point cloud data and sending them to a host computer; a UWB tag, arranged on the drone, for communicating with a UWB base station deployed in the mine, obtaining the distance between the drone and different UWB base stations, obtaining the position information of the drone in the mine and sending it to the host computer; a host computer, for receiving and processing information sent from the lower computer, the 360 ​​laser radar and the UWB tag, obtaining the final drone posture information after fusion, and generating a position control instruction.

[0008] The present invention provides a preferred solution, wherein the sensor group includes a gyroscope, a magnetometer, an accelerometer, a downward-looking laser ranging radar and an optical flow sensor; the magnetometer obtains the orientation information of the drone head, the gyroscope and the accelerometer data are integrated to provide the attitude angle and three-axis acceleration information of the drone, the downward-looking laser ranging radar obtains the altitude information of the drone, and the optical flow sensor runs an optical flow algorithm and estimates the velocity information of the drone in the horizontal plane in combination with the drone altitude.

[0009] In the second aspect, the present invention provides a drone system, which adopts the above-mentioned mine inspection drone positioning system based on laser radar and UWB ranging, including: an actuator, used to perform corresponding movements according to the motion control signal sent by the lower computer; a power module, used to power the upper computer, the lower computer, the sensor group and the actuator; the UWB tag is also used to receive the task instructions and / or motion instructions sent by the UWB base station and send them to the upper computer; the lower computer is also used to receive the position control instructions from the upper computer, and generate the motion control signal in combination with the final drone posture information; the upper computer is also used to generate the expected control instructions in combination with the current flight mission and pass them to the lower computer for execution.

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

[0011] The mine inspection UAV and positioning system based on laser radar and UWB ranging of the present invention is a real-time positioning system for mines with UWB base stations deployed. Through 360 laser radar and UWB ranging, it can adapt to the positioning of UAVs in mine environments, so that UAVs can fly safely in mine environments with dim light and long-term closure leading to dust spread, and can accurately locate and land in a preset hangar when necessary, solving the key problem of autonomous inspection of UAVs in mines and expanding the application scenarios of UAV systems in inspection tasks.

[0012] The present invention obtains the position and posture of the UAV in the launching inertial system through the laser radar, which is used for feedback control by the position and speed control module. At the same time, by obtaining the distance to the UWB base station, the approximate position of the UAV in the mine and the relative position relationship with the hangar are obtained, thereby realizing the preliminary positioning of the landing point by the UAV, which is conducive to the subsequent accurate positioning and landing of the UAV in the preset hangar, so that the UAV can subsequently complete functions such as charging, cleaning and data transmission in the hangar, providing a basis for realizing autonomous and regular inspections of UAVs in mines. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0014] Figure 1 A module block diagram of a mine inspection drone system based on laser radar and UWB ranging provided by a specific embodiment of the present invention;

[0015] Figure 2 A block diagram of the internal modules and signal flows of the host computer, flight control board, 360 laser radar, and UWB tag in a mine inspection drone system based on laser radar and UWB ranging provided in a specific embodiment of the present invention.

[0016] Figure numerals: 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, posture fusion module 211, attitude control module 212, 360 laser radar 31, UWB tag 32, upper computer 4, positioning and attitude module 41, obstacle avoidance and centering module 42, speed control module 43, position control module 44, flight mission module 45, flight status module 46, power module 5, battery 51, first DC-DC module 52, second DC-DC module 53, actuator 6, electronic speed regulator 61, brushless motor 62, blades 63, external safety assurance module 7, remote control 71. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Embodiment 1

[0019] Please refer to Figure 1 This embodiment provides a mine inspection drone positioning system based on laser radar and UWB ranging, which is mainly composed of a sensor group 1, a lower computer 2, a 360 laser radar 31 (preferably a path-seeking 360 laser radar 31), a UWB tag 32 and an upper computer 4. This embodiment also provides a drone system, which uses the above-mentioned mine inspection drone positioning system based on laser radar and UWB ranging, and mainly includes an actuator 6 and a power module 5. In a preferred embodiment, the drone system is also provided with an external safety assurance module 7, that is, the drone system is mainly composed of six parts: an upper computer 4, a lower computer 2, a sensor group 1, a power module 5, an actuator 6 and an external safety assurance module 7.

[0020] After receiving the data from the Midao 360 laser radar 31, the host computer 4 will run the FAST-LIO algorithm to obtain the position and attitude of the drone in the transmitting inertial system. The lower computer 2 will receive this information and integrate the speed estimation information of the drone and the attitude information such as the pitch angle and roll angle provided by the sensor module to obtain a more accurate state quantity of the drone. The lower computer 2 transmits the state quantity of the drone to the host computer 4, and calculates the expected control quantity based on the control requirements and transmits it to the lower computer 2 for execution. The actuator 6 provides power for the flight of the drone. The power module 5 provides power support for airborne systems such as the host computer 4, the lower computer 2, the sensor group 1 and the actuator 6.

[0021] The upper computer 4, the lower computer 2 and the sensor group 1 in this embodiment are described in detail below. The UWB tag 32 on the drone can obtain the distances of different UWB base stations within the relative communication range by communicating with the self-deployed UWB base station, thereby obtaining the position in the mine. At the same time, the UWB base station will receive instructions issued by the central control platform and send them to the UWB tag 32, thereby changing the current task of the drone. Among them:

[0022] The sensor group 1 includes a variety of sensors for obtaining the preliminary status information of the drone and sending it to the lower computer 2. The sensor group 1 of this embodiment is mainly composed 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, according to the application and performance requirements, the sensors directly connected to the flight control used in the present invention are: 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 system with the nose orientation information, and the gyroscope 11 and the accelerometer 13 data are integrated to provide the attitude angle and three-axis acceleration information for the drone system. The optical flow sensor 15 and the downward-looking laser ranging radar 14 are external sensors, wherein the optical flow sensor 15 is a low-resolution downward-mounted camera. By running the optical flow algorithm and combining the height of the drone, the speed information of the drone system in the horizontal plane can be estimated. The downward-looking laser ranging radar 14 can measure accurate height information after being placed downward. The remote control receiver 16 and the remote control 71 in the external safety assurance module 7 are a set of signal receiving and sending devices. By the pilot toggling the control stick in the remote control 71, the drone can be forced to jump from the program control mode to the manual control mode, thereby ensuring the flight safety of the drone system.

[0023] The lower computer 2 has a built-in data fusion module, which is used to fuse the preliminary UAV posture information obtained by various sensors, obtain accurate UAV posture information, and send it to the upper computer 4. The lower computer 2 is also used to receive the position control command from the upper computer 4, and generate a motion control signal in combination with the final UAV posture information. More preferably, according to the application and performance requirements, this embodiment uses PIXHWAK mini6 c as the lower computer 2, that is, the flight control board 21. The flight control board 21 runs a sensor data fusion algorithm, which obtains accurate position, speed, acceleration, attitude and other status information of the UAV system by fusing the data of built-in sensors such as the magnetometer 12, gyroscope 11 and accelerometer 13 and external sensors such as the optical flow sensor 15 and the downward-looking laser ranging radar 14, and generates a PWM signal for controlling the motor speed by combining the control command received from the upper computer 4 with the status information. The PWM signal is then transmitted to the electronic speed regulator 61 of the actuator 6 for controlling the speed of the brushless motor 62.

[0024] The host computer 4 is used to receive and process the information sent from the lower computer 2, the 360 ​​laser radar 31 and the UWB tag 32, obtain the final UAV posture information after fusion, and generate position control instructions. The host computer 4 is also used to generate the desired control instructions in combination with the current flight mission and pass them to the lower computer 2 for execution. More preferably, according to the application and performance requirements, the present invention uses NVIDIA Jetson TX2 NX as the host computer 4. The host computer 4 is an integrated module, and a state machine system runs on the board. It will receive information sent from the lower computer 2, UWB and other modules, generate the desired control instructions in combination with the current flight mission, and pass them to the flight control board 21 for execution. The control instructions in the present invention are the desired attitude angle and the desired thrust of the UAV, on this basis, the most flexible and safe control of the UAV system can be performed.

[0025] External sensors, this part mainly includes the Midao 360 laser radar 31 and the UWB tag 32 directly connected to the host computer 4. Among them, the Midao 360 laser radar 31 obtains IMU data and laser point cloud data and sends them to the host computer 4. The Midao 360 laser radar 31 is a medium-wavelength laser radar selected according to the mine cave environment, which has a certain penetration type for the dust inside the mine cave, thereby ensuring that the laser data is the real obstacle or wall distance. The laser radar can achieve 360 ​​degrees in the horizontal direction and 59 degrees in the vertical direction, so that the obstacle information in the three-dimensional space can be better scanned and sent to the host computer 4 in the form of point cloud data. At the same time, the sensor itself has an IMU to achieve more accurate motion estimation. The UWB tag 32 is set on the drone and is used to communicate with the UWB base station that has been deployed in the mine cave, obtain the distance between the drone and different UWB base stations, obtain the location information of the drone in the mine cave and send it to the host 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 host computer 4. The UWB tag 32 is a supporting product of the original UWB base station in the mine, and is generally used to obtain the position of miners or other underground equipment. In this embodiment, it is directly used on the drone to calculate the approximate relative position of the drone and the hangar. At the same time, the UWB tag 32 can realize data transmission as a communication device.

[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 rotation speed of the four brushless motors 62, and the four brushless motors 62 respectively drive the four groups of blades 63 to rotate.

[0027] The power module 5 is used to supply power to the host computer 4, the slave computer 2, the sensor group 1 and the actuator 6. The power module 5 mainly includes a battery 51, a first DC-DC module 52 and a second DC-DC module 53. The first DC-DC module 52 outputs a 5V DC voltage to supply power to the flight control board 21. The second DC-DC module 53 outputs a 12V DC voltage to provide voltage for the operation of the host computer.

[0028] Embodiment 2

[0029] Please refer to Figure 2 , this embodiment provides a more preferred mine inspection drone positioning system based on laser radar and UWB ranging. The host computer 4 is built with: a positioning and attitude module 41, which is used to obtain the position and attitude information of the drone based on the IMU data and the point cloud data. The obstacle avoidance and centering module 42 is used to generate an obstacle avoidance and centering instruction based on the acquired point cloud data. The speed control module 43 is used to generate a corresponding speed control instruction based on the obstacle avoidance and centering instruction. The position control module 44 is used to generate a position control instruction based on the speed control instruction. The flight mission module 45 is used to receive the task instructions and motion instructions from the UWB tag 32 according to the custom protocol, and then issue instructions to the obstacle avoidance and centering module 42 and / or the flight status module 46. The flight status module 46 is used to generate the corresponding flight state according to the instructions issued by the flight mission module 45, and send the target state change to the position control module 44; the position control module 44 adjusts the position according to the target state change and generates a position control instruction.

[0030] The lower computer 2 is built with: a posture fusion module 211, which is used to fuse the preliminary UAV posture information obtained from multiple sensors with the position and attitude information of the UAV obtained by the positioning and attitude module 41 in the upper computer 4, obtain the final accurate position and attitude information of the UAV, and send it to the upper computer 4; the position control module 44 of the upper computer 4 generates a position control instruction according to the final accurate position and attitude information of the UAV, and sends it to the attitude control module 212 of the lower computer 2. The attitude control module 212 generates a UAV flight attitude control instruction according to the position control instruction generated by the position control module 44 in the upper computer 4 and sends it to the actuator 6.

[0031] Embodiment 2 The above modules are as shown in the attached Figure 2 Information is transmitted in a certain way, which jointly ensures the basic flight capability of the drone and its ability to interact with the outside world.

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

[0033] FAST-LIO combines data from LiDAR and Inertial Measurement Unit (IMU) to achieve high-precision pose estimation through a tightly coupled iterative extended Kalman filter (EKF). The algorithm performs well in fast motion, noisy or cluttered environments, and is characterized by high computational efficiency and strong robustness. Data Fusion: FAST-LIO uses a tightly coupled iterative extended Kalman filter to fuse LiDAR feature points and IMU data. This filter is capable of handling nonlinear systems and approximates the true state through iterative optimization. In the filter, LiDAR feature points and IMU data are used together to construct a residual function, and the state estimate is updated by minimizing the residual. Feature Extraction: FAST-LIO extracts planar features and edge features from the LiDAR point cloud, 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: The extracted feature points are used together with the IMU integration results for point cloud matching to estimate the relative pose. IMU data is used for integration to obtain a preliminary estimate of relative pose, which helps maintain the stability of the algorithm when LiDAR data is sparse or noisy. At the same time, the IMU integration result is also used to perform motion compensation on 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 fields of robots, drones, etc., especially in pose (position and attitude) estimation. EKF2 is a nonlinear version of the classic Kalman filter and is suitable for processing nonlinear systems. It estimates the state of the system by linearizing the nonlinear system and using the state equation and observation equation of the system. In pose fusion, EKF2 can fuse data from different sensors, such as inertial measurement unit (IMU), GPS, laser rangefinder, vision sensor, etc., to provide accurate position and attitude estimation.

[0035] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0036] The above-described embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. The mine inspection drone positioning system based on laser radar and UWB ranging is characterized by: include: The sensor group includes a variety of sensors, which are used to obtain the initial status information of the drone and send it to the lower computer; The lower computer has a built-in data fusion module, which is used to fuse the preliminary UAV posture information obtained by multiple sensors, obtain accurate UAV posture information, and send it to the upper computer; 360 laser radar, obtains IMU data and laser point cloud data and sends them to the host computer; The UWB tag is installed on the drone and used to communicate with the UWB base stations deployed in the mine, obtain the distance between the drone and different UWB base stations, obtain the location information of the drone in the mine and send it to the host computer; The upper computer is used to receive and process the information sent by the lower computer, 360 laser radar and UWB tag, obtain the final drone posture information after fusion, and generate position control instructions.

2. The mine inspection drone positioning system based on laser radar and UWB ranging according to claim 1 is characterized in that: The sensor group includes a gyroscope, a magnetometer, an accelerometer, a downward-looking laser ranging radar and an optical flow sensor; the magnetometer obtains the UAV head orientation information, the gyroscope and accelerometer data are integrated to provide the UAV attitude angle and three-axis acceleration information, the downward-looking laser ranging radar obtains the UAV height information, and the optical flow sensor runs an optical flow algorithm and estimates the UAV speed information in the horizontal plane in combination with the UAV height.

3. The mine inspection drone positioning system based on laser radar and UWB ranging according to claim 1 is characterized in that: The lower computer adopts a flight control board, the magnetometer, gyroscope and accelerometer are built-in integrated sensors of the flight control board, and the downward-looking laser ranging radar and optical flow sensor are external sensors.

4. The mine inspection drone positioning system based on laser radar and UWB ranging according to claim 1 is characterized in that: The 360 ​​laser radar is a medium-wavelength laser radar selected according to the mine environment, which 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 ​​laser radar has its own IMU, which obtains IMU data and sends it to the host computer; the host computer has built-in: Positioning and attitude determination module, used to obtain the position and attitude information of the drone based on IMU data and point cloud data; The obstacle avoidance and centering module is used to generate obstacle avoidance and centering instructions based on the acquired point cloud data; A speed control module is used to generate corresponding speed control instructions according to obstacle avoidance and centering instructions; The position control module is used to generate a position control instruction according to the speed control instruction.

5. The mine inspection drone positioning system based on laser radar and UWB ranging according to claim 4 is characterized in that: The host computer also includes: The flight mission module is used to receive mission instructions and motion instructions from the UWB tag according to a custom protocol, and then issue instructions to the obstacle avoidance and centering module and / or the flight status module; The flight status module is used to generate the corresponding flight status according to the instructions issued by the flight mission module and send the target status changes to the position control module; the position control module adjusts the position according to the target status changes and generates position control instructions.

6. The mine inspection drone positioning system based on laser radar and UWB ranging according to claim 5 is characterized in that: The lower computer comprises: The position and attitude fusion module is used to fuse the preliminary UAV position and attitude information obtained from multiple sensors with the position and attitude information of the UAV obtained by the positioning and attitude determination module in the host computer, obtain the final accurate position and attitude information of the UAV, and send it to the host computer; the position control module of the host computer generates a position control instruction based on the final accurate position and attitude information of the UAV, and sends it to the attitude control module of the lower computer; The attitude control module generates the UAV flight attitude control instruction according to the position control instruction generated by the position control module in the host computer and sends it to the actuator.

7. The mine inspection drone positioning system based on laser radar and UWB ranging according to claim 6 is characterized in that: The obstacle avoidance and centering module adopts an artificial potential field algorithm; the FAST-LIO algorithm; the flight state module simulates and manages the different flight states and state changes of the UAV through a finite state machine; the posture fusion module adopts the EKF2 UAV position fusion algorithm; and the attitude control module is implemented through a cascade PID control system.

8. An unmanned aerial vehicle system, using the mine inspection unmanned aerial vehicle positioning system based on laser radar and UWB ranging as described in any one of claims 1 to 7, characterized in that: include: An actuator is used to execute corresponding motion according to the motion control signal sent by the lower computer; The power module is used to supply power to the host computer, the slave computer, the sensor group and the actuator; the UWB tag is also used to receive the 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 the position control instructions from the host computer, and generate motion control signals in combination with the final UAV posture information; the host computer is also used to generate the expected control instructions in combination with the current flight mission and transmit them to the slave computer for execution.

9. The drone system according to claim 8, characterized in that: The sensor group also includes a remote control receiver; the drone system also includes an external safety assurance module, including a remote control for sending manual remote control instructions to the remote control receiver; the remote control receiver receives the manual remote control instructions and sends them to the lower computer.

10. The drone system according to claim 8, characterized in that: The actuator includes an electronic speed regulator, 4 brushless motors and 4 groups of blades; the electronic speed regulator is used to control the speed of the 4 brushless motors, and the 4 brushless motors drive the 4 groups of blades to rotate respectively; the motion control signal generated by the lower computer is a PWM signal for controlling the speed of the brushless motor, and the PWM signal is transmitted to the electronic speed regulator for controlling the speed of the brushless motor.

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