Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 13 of 13
Full-Text Articles in Engineering
Fault Tolerant Robotics Using Active Diagnosis Of Partially Observable Systems And Optimized Path Planning For Underwater Message Ferrying, Devon M. Webb
Theses and Dissertations
Underwater robotic vehicles are used in a variety of environments that would be dangerous for humans. For these vehicles to be successful, they need to be tolerant of a variety of internal and external faults. To be resilient to internal faults, the system must be capable of determining the source of faulty behavior. However many different faults within a robotic vehicle can create identical faulty behavior, which makes the vehicles impossible to diagnose using conventional methods. I propose a novel active diagnosis method for differentiating between faults that would otherwise have identical behavior. I apply this method to a communication …
Integration Of A Complete Detect And Avoid System For Small Unmanned Aircraft Systems, Jared Kevin Wikle
Integration Of A Complete Detect And Avoid System For Small Unmanned Aircraft Systems, Jared Kevin Wikle
Theses and Dissertations
For unmanned aircraft systems to gain full access to the National Airspace System (NAS), they must have the capability to detect and avoid other aircraft. This research focuses on the development of a detect-and-avoid (DAA) system for small unmanned aircraft systems. To safely avoid another aircraft, an unmanned aircraft must detect the intruder aircraft with ample time and distance. Two analytical methods for finding the minimum detection range needed are described. The first method, time-based geometric velocity vectors (TGVV), includes the bank-angle dynamics of the ownship while the second, geometric velocity vectors (GVV), assumes an instantaneous bank-angle maneuver. The solution …
Airborne Collision Detection And Avoidance For Small Uas Sense And Avoid Systems, Laith Rasmi Sahawneh
Airborne Collision Detection And Avoidance For Small Uas Sense And Avoid Systems, Laith Rasmi Sahawneh
Theses and Dissertations
The increasing demand to integrate unmanned aircraft systems (UAS) into the national airspace is motivated by the rapid growth of the UAS industry, especially small UAS weighing less than 55 pounds. Their use however has been limited by the Federal Aviation Administration regulations due to collision risk they pose, safety and regulatory concerns. Therefore, before civil aviation authorities can approve routine UAS flight operations, UAS must be equipped with sense-and-avoid technology comparable to the see-and-avoid requirements for manned aircraft. The sense-and-avoid problem includes several important aspects including regulatory and system-level requirements, design specifications and performance standards, intruder detecting and tracking, …
Development Of A Sense And Avoid System For Small Unmanned Aircraft Systems, Robert Andrew Klaus
Development Of A Sense And Avoid System For Small Unmanned Aircraft Systems, Robert Andrew Klaus
Theses and Dissertations
Unmanned aircraft systems (UAS) represent the future of modern aviation. Over the past 10 years their use abroad by the military has become commonplace for surveillance and combat. Unfortunately, their use at home has been far more restrictive. Due to safety and regulatory concerns, UAS are prohibited from flying in the National Airspace System without special authorization from the FAA. One main reason for this is the lack of an on-board pilot to "see and avoid" other air traffic and thereby maintain the safety of the skies. Development of a comparable capability, known as "Sense and Avoid" (SAA), has therefore …
Developing A Guidance Law For A Small-Scale Controllable Projectile Using Backstepping And Adaptive Control Techniques And A Hardware System Implementation For A Uav And A Ugv To Track A Moving Ground Target, Kevin Christopher Meier
Developing A Guidance Law For A Small-Scale Controllable Projectile Using Backstepping And Adaptive Control Techniques And A Hardware System Implementation For A Uav And A Ugv To Track A Moving Ground Target, Kevin Christopher Meier
Theses and Dissertations
The work in this thesis is on two topics. The first topic focuses on collaboration between a UAV and a UGV to track a moving ground target. The second topic focuses on deriving a guidance law for a small-scale controllable projectile to be guided into a target. For the first topic, we implement a path planning algorithm in a hardware system for a UAV and UGV to track a ground target. The algorithm is designed for urban environments where it is common for objects to obstruct sensors located on the UAV and the UGV. During the hardware system's implementation, multiple …
Bearing-Only Cooperative-Localization And Path-Planning Of Ground And Aerial Robots, Rajnikant Sharma
Bearing-Only Cooperative-Localization And Path-Planning Of Ground And Aerial Robots, Rajnikant Sharma
Theses and Dissertations
In this dissertation, we focus on two fundamental problems related to the navigation of ground robots and small Unmanned Aerial Vehicle (UAVs): cooperative localization and path planning. The theme running through in all of the work is the use of bearing only sensors, with a focus on monocular video cameras mounted on ground robots and UAVs. To begin with, we derive the conditions for the complete observability of the bearing-only cooperative localization problem. The key element of this analysis is the Relative Position Measurement Graph (RPMG). The nodes of an RPMG represent vehicle states and the edges represent bearing measurements …
Vision-Based Path Planning, Collision Avoidance, And Target Tracking For Unmanned Air And Ground Vehicles In Urban Environments, Huili Yu
Theses and Dissertations
Unmanned vehicle systems, specifically Unmanned Air Vehicles (UAVs) and Unmanned Ground Vehicles (UGVs) have found potential use in both military and civilian applications. For many applications, unmanned vehicle systems are required to navigate in urban environments where obstacles with various types and sizes exist. The main contribution of this research is to offer vision-based path planning, collision avoidance, and target tracking strategies for Unmanned Air and Ground vehicles operating in urban environments. Two vision-based local-level frame mapping and planning techniques are first developed for Miniature Air Vehicles (MAVs). The techniques build maps and plan paths in the local-level frame of …
Multi-Resolution Obstacle Mapping With Rapidly-Exploring Random Tree Path Planning For Unmanned Air Vehicles, Brett Wayne Millar
Multi-Resolution Obstacle Mapping With Rapidly-Exploring Random Tree Path Planning For Unmanned Air Vehicles, Brett Wayne Millar
Theses and Dissertations
Unmanned air vehicles (UAVs) have become an important area of research. UAVs are used in many environments which may have previously unknown obstacles or sources of danger. This research addresses the problem of obstacle mapping and path planning while the UAV is in flight. Online obstacle mapping is achieved through the use of a multi-resolution map. As sensor information is received, a quadtree is built up to hold the information based upon the uncertainty associated with the measurement. Once a quadtree map of obstacles is built up, we desire online path re-planning to occur as quickly as possible. We introduce …
System Identification, State Estimation, And Control Of Unmanned Aerial Robots, Caleb H. Chamberlain
System Identification, State Estimation, And Control Of Unmanned Aerial Robots, Caleb H. Chamberlain
Theses and Dissertations
This thesis describes work in a variety of topics related to aerial robotics, including system identification, state estimation, control, and path planning. The path planners described in this thesis are used to guide a fixed-wing UAV along paths that optimize the aircraft's ability to track a ground target. Existing path planners in the literature either ignore occlusions entirely, or they have limited capability to handle different types of paths. The planners described in this thesis are novel in that they specifically account for the effect of occlusions in urban environments, and they can produce a much richer set of paths …
Search Pattern Generation And Path Management For Search Over Rough Terrain With A Small Uav, Jacob L. Bishop
Search Pattern Generation And Path Management For Search Over Rough Terrain With A Small Uav, Jacob L. Bishop
Theses and Dissertations
Search operations can be described by the interaction between three entities: the target, the sensor, and the environment. Past treatments of the search problem have focused primarily on the interaction between the sensor and the target. The effects that the environment has on the target and sensor have been greatly simplified or ignored completely. The wilderness search and rescue scenario is one case in which these interactions cannot be safely ignored. Using the wilderness search and rescue problem as our motivating example, we develop an algorithm for planning search paths for a small unmanned aerial vehicle (UAV) over rough terrain …
Path Planning For Unmanned Air And Ground Vehicles In Urban Environments, Andrew B. Curtis
Path Planning For Unmanned Air And Ground Vehicles In Urban Environments, Andrew B. Curtis
Theses and Dissertations
Unmanned vehicle systems, specifically unmanned air vehicles (UAVs) and unmanned ground vehicles (UGVs), have become a popular research topic. This thesis discusses the potential of a UAV-UGV system used to track a human moving through complex urban terrain. This research focuses on path planning problems for both a UAV and a UGV, and presents effective solutions for both problems. In the UAV path planning problem, we desire to plan a path for a miniature fixed-wing UAV to fly through known urban terrain without colliding with any buildings. We present the Waypoint RRT (WRRT) algorithm, which accounts for UAV dynamics while …
Obstacle Avoidance For Small Unmanned Air Vehicles, Brandon R. Call
Obstacle Avoidance For Small Unmanned Air Vehicles, Brandon R. Call
Theses and Dissertations
Small UAVs are used for low altitude surveillance flights where unknown obstacles can be encountered. These UAVs can be given the capability to navigate in uncertain environments if obstacles are identified. This research presents an obstacle avoidance system for small UAVs. First, a mission waypoint path is created that avoids all known obstacles using a genetic algorithm. Then, while the UAV is in flight, obstacles are detected using a forward looking, onboard camera. Image features are found using the Harris Corner Detector and tracked through multiple video frames which provides three dimensional localization of the features. A sparse three dimensional …
Coordinated Uav Target Assignment Using Distributed Calculation Of Target-Task Tours, David H. Walker
Coordinated Uav Target Assignment Using Distributed Calculation Of Target-Task Tours, David H. Walker
Theses and Dissertations
This thesis addresses the improvement of cooperative task allocation to vehicles in multiple-vehicle, multiple-target scenarios through the use of more effective preplanned tours. Effective allocation of vehicles to targets requires knowledge of both the team objectives and the contributions that individual vehicles can make toward accomplishing team goals. This is primarily an issue of individual vehicle path planning --- determining the path the vehicles will follow to accomplish individual and team goals. Conventional methods plan optimal point-to-point path segments that often result in lengthy and suboptimal tours because the trajectory neither considers future tasks nor the overall path. However, cooperation …