학위논문 (박사)-- 서울대학교 대학원 : 기계항공공학부, 2016. 8. 김유단. ; Diverse research topics on Unmanned Aerial Vehicles (UAVs) have emerged as the UAV has received great attention due to lots of advantages. Among its numerous applications, shape mapping is an important means of collecting information of an unknown environment. As the UAV has been used as a platform in the shape mapping, an appropriate path must be generated to efficiently map an object. Furthermore, to successfully perform missions including the shape mapping, the UAV must have the ability to detect and avoid obstacles of various shapes using the obstacle information acquired by an onboard sensor. This is critical because a collision with these obstacles may result in fatal damage and potentially mission failure. In this dissertation, a guidance law for obstacle shape mapping and reactive collision avoidance is proposed. A quadrotor dynamic model is constructed, and a control system is designed based on the feedback linearization and linear quadratic tracker techniques. A stereo vision system with a limited field of view and sensing range is assumed to be mounted on the quadrotor to obtain obstacle information by utilizing a depth map. For shape mapping, the states of the quadrotor are used to generate a path for appropriate obstacle mapping in real time. The quadrotor moves around the obstacle to map the overall shape of the obstacle while avoiding collisions. The quadrotor performs horizontal and vertical maneuvers if the image plane of the vision system cannot cover the entire obstacle. The horizontal and vertical maneuvers are performed in sequence to develop a systematic scheme to efficiently map the obstacle. For collision avoidance, an ellipsoid is chosen as a circumscribed bounding box to contain the acquired obstacle data points, which can be obtained by solving a convex optimization problem. An affine transformation is used to form a collision cone consisting of straight lines tangent to the ellipsoid. A collision condition is examined using the collision cone and velocity vector of the quadrotor. A hierarchical clustering method is proposed to deal with multiple obstacles, and the bounding boxes are updated using the clusters. Numerical simulations including a Monte Carlo simulation are performed to demonstrate the performance of the proposed shape mapping and collision avoidance algorithms. ; Chapter 1 Introduction 1 1.1 Background and Motivation 1 1.2 Literature Survey 5 1.3 Objectives 11 1.4 Research Contributions 12 1.5 Dissertation Organization 13 Chapter 2 Quadrotor System Model 15 2.1 Quadrotor Dynamics 15 2.2 Control System Design 19 2.2.1 Position Controller 21 2.2.2 Velocity Controller 24 2.2.3 Numerical Simulation 25 Chapter 3 Depth Map and Obstacle Information Acquisition 30 3.1 Depth Map Modeling 30 3.2 Acquisition of Obstacle Data 34 Chapter 4 Guidance Law for Obstacle Shape Mapping 37 4.1 Guidance Algorithm for Mapping 38 4.1.1 Horizontal Path Command 38 4.1.2 Yaw Command 41 4.1.3 Height Command 44 4.1.4 Horizontal Maneuver and Vertical Maneuver 46 4.2 Data Management 52 4.3 Numerical Simulation and Analysis 54 4.3.1 Simulation I: Long Obstacle Along y Axis 54 4.3.2 Simulation II: Obstacle with Potential Threat 60 4.3.3 Simulation III: Tall Obstacle Along z Axis 65 4.3.4 Simulation Iv: Practical Application 73 Chapter 5 Guidance Law for Reactive Collision Avoidance 78 5.1 Formation of Collision Cone 78 5.1.1 Sphere as a Bounding Box 79 5.1.2 Ellipsoid as a Bounding Box 80 5.1.3 Collision Cone 81 5.2 Collision Avoidance Law 86 5.2.1 Collision Condition 86 5.2.2 Velocity and Yaw Commands 88 5.3 Handling Multiple Obstacles using Hierarchical Clustering 91 5.4 Numerical Simulation and Analysis 98 5.4.1 Simulation I: Single Obstacle 98 5.4.2 Simulation II: Multiple Obstacles 104 5.4.3 Simulation III: Application 113 Chapter 6 Conclusions 116 6.1 Concluding Remarks 116 6.2 Future research works 117 Bibliography 119 Appendix 132 국문 초록 136 ; Doctor


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    Title :

    Depth Map based Guidance Law of Quadrotor System for Obstacle Shape Mapping and Reactive Collision Avoidance ; 장애물 형상매핑과 반응적 충돌회피를 위한 깊이지도 기반 쿼드로터 유도법칙



    Publication date :

    2016-01-01


    Type of media :

    Theses


    Type of material :

    Electronic Resource


    Language :

    English



    Classification :

    DDC:    629





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