Vision Guidance Controller for an Unmanned Aerial Vehicle


Book Description

The use of Unmanned Aerial Vehicles (UAVs) in modern military operations for reconnaissance and other missions continues to grow. UAV systems using remote control guidance are limited in range and subject to Electronic Warfare concerns. Guidance Systems using only Global Positioning Service (GPS) or an Inertial Navigation System (INS) are limited to a pre-programmed route of flight. A vision guidance system that can control the UAV over an arbitrary course is not subject to these limitations. This thesis uses classical control methods to develop and test an autonomous vision controller for the FOG-R UAV (FROG). First, a computer model of the camera output for a flight that tracks a river is made to develop the controller and to test it in nonlinear simulation. Finally, the complete system is flight tested on the FROG UAV. The design and test equipment include a highly modified FOG-R UAV from the U.S. Army, the MATRIXx Product Family of software tools developed by Integrated Systems, Inc., and a Ground Station built at NPS from commercially available computer and communication equipment.




An Onboard Vision System for Unmanned Aerial Vehicle Guidance


Book Description

The viability of small Unmanned Aerial Vehicles (UAVs) as a stable platform for specific application use has been significantly advanced in recent years. Initial focus of lightweight UAV development was to create a craft capable of stable and controllable flight. This is largely a solved problem. Currently, the field has progressed to the point that unmanned aircraft can be carried in a backpack, launched by hand, weigh only a few pounds and be capable of navigating through unrestricted airspace.




Visual Guidance of Unmanned Aerial Manipulators


Book Description

This monograph covers theoretical and practical aspects of the problem of autonomous guiding of unmanned aerial manipulators using visual information. For the estimation of the vehicle state (position, orientation, velocity, and acceleration), the authors propose a method that relies exclusively on the use of low-cost and highrate sensors together with low-complexity algorithms. This is particularly interesting for applications in which on board computation with low computation power is needed. Another relevant topic covered in this monograph is visual servoing. The authors present an uncalibrated visual servo scheme, capable of estimating at run time, the camera focal length from the observation of a tracked target. The monograph also covers several control techniques, which achieve a number of tasks, such as robot and arm positioning, improve stability and enhance robot arm motions. All methods discussed in this monograph are demonstrated in simulation and through real robot experimentation. The text is appropriate for readers interested in state estimation and control of aerial manipulators, and is a reference book for people who work in mobile robotics research in general.




A Gimbal-supported, Mono Camera, Relative Position Measurement System of a Visually Distinct Object for UAV Guidance


Book Description

This thesis describes a vision-based system for measuring distance and bearing between an unmanned aerial vehicle (UAV) and a ground object. The system is built of a single camera, mounted on a gimbal, which stabilizes camera attitude. The novelty of this system is that it uses a single camera and tracks a single object on the ground, hence requiring less equipment compared to other types of vision-based navigation systems. Vision system data estimates are fed into the controller to stabilize aircraft on a circular orbit and to maintain fully automated flight, without GPS data. The system can be used as a backup in the case of GPS signal loss. In that case, the UAV will orbit a target until the signal is restored or manual input is received. We describe the hardware chosen to solve this problem and the image-processing and rectification algorithms that determine the position of the target. The position data is used to control the autopilot which was optimized for circling the target. The real flight test results for the system, installed on a fixed-wing UAV, are presented.




Vision-Based Tracking for Unmanned Aerial Vehicles


Book Description

This paper presents the design of a vision-based controller for an underactuated, unmanned aerial vehicle (UAV) equipped with a pan-tilt camera unit (PTCU) to achieve the objective of following a leader vehicle autonomously. The relative position and orientation information is obtained from the monocular camera utilizing homography-based techniques. The proposed controller, built upon Lyapunov design methods, achieves uniform ultimate bounded (UUB) tracking. As an extension, it is also demonstrated that the approach used in the development of the control strategy for the leaderfollower problem can be applied, with a few modifications, to the problem of trajectory tracking, where the desired trajectory is described as a sequence of images taken, for example, by the on-board camera during a previous flight.




Fault-tolerant Flight Control and Guidance Systems


Book Description

This book offers a complete overview of fault-tolerant flight control techniques. Discussion covers the necessary equations for the modeling of small UAVs, a complete system based on extended Kalman filters, and a nonlinear flight control and guidance system.




Stochastically Optimized Monocular Vision-based Navigation and Guidance


Book Description

The objective of this thesis is to design a relative navigation and guidance system for unmanned aerial vehicles (UAVs) for vision-based control applications. The vision-based navigation, guidance and control has been one of the most focused on research topics for the automation of UAVs. This is because in nature, birds and insects use vision as the exclusive sensor for object detection and navigation. In particular, this thesis studies the monocular vision-based navigation and guidance. Since 2-D vision-based measurements are nonlinear with respect to the 3-D relative states, an extended Kalman filter (EKF) is applied in the navigation system design. The EKF-based navigation system is integrated with a real-time image processing algorithm and is tested in simulations and flight tests. The first closed-loop vision-based formation flight has been achieved. In addition, vision-based 3-D terrain recovery was performed in simulations. A vision-based obstacle avoidance problem is specially addressed in this thesis. A navigation and guidance system is designed for a UAV to achieve a mission of waypoint tracking while avoiding unforeseen stationary obstacles by using vision information. A 3-D collision criterion is established by using a collision-cone approach. A minimum-effort guidance (MEG) law is applied for a guidance design, and it is shown that the control effort can be reduced by using the MEG-based guidance instead of a conventional guidance law. The system is evaluated in a 6 DoF flight simulation and also in a flight test. For monocular vision-based control problems, vision-based estimation performance highly depends on the relative motion of the vehicle with respect to the target. Therefore, this thesis aims to derive an optimal guidance law to achieve a given mission under the condition of using the EKF-based relative navigation. Stochastic optimization is formulated to minimize the expected cost including the guidance error and the control effort. A suboptimal guidance law is derived based on an idea of the one-step-ahead (OSA) optimization. Simulation results show that the suggested guidance law significantly improves the guidance performance. Furthermore, the OSA optimization is generalized as the n-step-ahead optimization for an arbitrary number of n, and their optimality and computational cost are investigated.




Handbook of Unmanned Aerial Vehicles


Book Description

The Handbook of Unmanned Aerial Vehicles is a reference text for the academic and research communities, industry, manufacturers, users, practitioners, Federal Government, Federal and State Agencies, the private sector, as well as all organizations that are and will be using unmanned aircraft in a wide spectrum of applications. The Handbook covers all aspects of UAVs, from design to logistics and ethical issues. It is also targeting the young investigator, the future inventor and entrepreneur by providing an overview and detailed information of the state-of-the-art as well as useful new concepts that may lead to innovative research. The contents of the Handbook include material that addresses the needs and ‘know how’ of all of the above sectors targeting a very diverse audience. The Handbook offers a unique and comprehensive treatise of everything one needs to know about unmanned aircrafts, from conception to operation, from technologies to business activities, users, OEMs, reference sources, conferences, publications, professional societies, etc. It should serve as a Thesaurus, an indispensable part of the library for everyone involved in this area. For the first time, contributions by the world’s top experts from academia, industry, government and the private sector, are brought together to provide unique perspectives on the current state-of-the-art in UAV, as well as future directions. The Handbook is intended for the expert/practitioner who seeks specific technical/business information, for the technically-oriented scientists and engineers, but also for the novice who wants to learn more about the status of UAV and UAV-related technologies. The Handbook is arranged in a user-friendly format, divided into main parts referring to: UAV Design Principles; UAV Fundamentals; UAV Sensors and Sensing Strategies; UAV Propulsion; UAV Control; UAV Communication Issues; UAV Architectures; UAV Health Management Issues; UAV Modeling, Simulation, Estimation and Identification; MAVs and Bio-Inspired UAVs; UAV Mission and Path Planning; UAV Autonomy; UAV Sense, Detect and Avoid Systems; Networked UAVs and UAV Swarms; UAV Integration into the National Airspace; UAV-Human Interfaces and Decision Support Systems; Human Factors and Training; UAV Logistics Support; UAV Applications; Social and Ethical Implications; The Future of UAVs. Each part is written by internationally renowned authors who are authorities in their respective fields. The contents of the Handbook supports its unique character as a thorough and comprehensive reference book directed to a diverse audience of technologists, businesses, users and potential users, managers and decision makers, novices and experts, who seek a holistic volume of information that is not only a technical treatise but also a source for answers to several questions on UAV manufacturers, users, major players in UAV research, costs, training required and logistics issues.




Unmanned Aerial Vehicles


Book Description

This book presents the basic tools required to obtain the dynamical models for aerial vehicles (in the Newtonian or Lagrangian approach). Several control laws are presented for mini-helicopters, quadrotors, mini-blimps, flapping-wing aerial vehicles, planes, etc. Finally, this book has two chapters devoted to embedded control systems and Kalman filters applied for aerial vehicles control and navigation. This book presents the state of the art in the area of UAVs. The aerodynamical models of different configurations are presented in detail as well as the control strategies which are validated in experimental platforms.




Development and Implementation of New Control Law for Vision Based Target Tracking System Onboard Small Unmanned Aerial Vehicles


Book Description

A new control law is being developed and implemented for the Vision Based Target Tracking (VBTT) system onboard a small unmanned aerial vehicle (SUAV). The new control law allows for coordinated SUAV guidance and vision-based target tracking of stationary and moving targets in the presence of atmospheric disturbances and measurements noise. The new control law is tested for its performance and stability in both the theoretical 6DOF simulation and the Hardware-in-the-Loop (HIL) simulation. Principal results show that realistic measures of performance of the control law are continuous and exhibit predictable degradation of performance with increase of target speed. The results are encouraging and comparable among theoretical predictions, actual hardware simulation results, and initial flight testing. The control law development, implementation, and trial processes and procedures are also examined and categorically documented in this thesis as future reference on the subject development, as well as for better knowledge retention, continuation and proliferation of the VBTT system.