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Autonomous Flight System of UAV through Global and Local Path Generation

전역 및 지역 경로 생성을 통한 무인항공기 자율비행 시스템 연구

  • Ko, Ha-Yoon (School of Electronics and Information Engineering, Korea Aerospace University) ;
  • Baek, Joong-Hwan (School of Electronics and Information Engineering, Korea Aerospace University) ;
  • Choi, Hyung-Sik (Korea Aerospace Research Institute)
  • 고하윤 (한국항공대학교 항공전자정보공학부) ;
  • 백중환 (한국항공대학교 항공전자정보공학부) ;
  • 최형식 (한국항공우주연구원 무인기체계부)
  • Received : 2018.12.11
  • Accepted : 2019.06.01
  • Published : 2019.06.30

Abstract

In this paper, a global and local flight path system for autonomous flight of the UAV is proposed. The overall system is based on the ROS robot operating system. The UAV in-built computer detects obstacles through 2-D Lidar and generates real-time local path and global path based on VFH and Modified $RRT^*$-Smart, respectively. Additionally, a movement command is issued based on the generated path on the UAV flight controller. The ground station computer receives the obstacle information and generates a 2-D SLAM map, transmits the destination point to the embedded computer, and manages the state of the UAV. The autonomous UAV flight system of the is verified through a simulator and actual flight.

본 논문에서는 무인항공기의 자율 비행을 위한 전역 및 지역 경로 비행 시스템을 제안한다. 전체적인 시스템은 ROS 로봇 운영체제를 기반으로 구축하였다. 무인항공기에 탑재된 임베디드 컴퓨터는 2-D Lidar를 이용하여 장애물을 검출하고, 실시간으로 VFH 기반의 지역 경로와 제안하는 Modified $RRT^*$-Smart 기반의 전역 경로를 생성한다. 또한, 무인항공기의 비행컨트롤러에 Mavros 통신 프로토콜을 이용하여 생성된 경로에 따른 이동 명령을 내린다. 지상국 컴퓨터는 장애물 정보를 수신하여 2-D SLAM 지도를 생성하고, 목적 지점을 임베디드 컴퓨터에 전달하며 무인항공기의 상태를 관장한다. 제안하는 무인항공기의 자율 비행 시스템을 3-D 공간 상의 시뮬레이터 및 실제 비행을 통해 검증하였다.

Keywords

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Fig. 1 Block Diagram of Autonomous Flight System

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Fig. 2 UAV and 2-D Lidar's TF Structure

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Fig. 3 GAZEBO Simulation

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Fig. 4 Rviz 3-D Visualization Tool

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Fig. 5 Local Avoidance Path Generation Based VFH

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Fig. 6 Polar Histogram and Threshold

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Fig. 7 Block Diagram of Modified RRT*-Smart Algorithm

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Fig. 8 RRT*-Smart Algorithm (left), Modified RRT*-Smart Algorithm (right)

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Fig. 9 Global Avoidance Path Generation (left), Local Avoidance Path Generation and Global Avoidance Path Regeneration by Proximity Obstacle (right)

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Fig. 10 Global Path Regeneration

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Fig. 11 UAV Used for Outdoor Flight

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Fig. 12 Outdoor Flight Environment

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Fig. 13 2-D Map and Global Path Flight

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Fig. 14 Local Avoidance Path Generation and Global Avoidance Path Regeneration by Proximity Obstacle (left), Global Avoidance Path Generation (right)

Table 1 Performance Comparison of RRT*-Smart and Modified RRT*-Smart

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Table 2 Main Components and Used Model

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Table 3 Specification of Intel NUC Embedded Computer

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