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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Autonomous guided vehicle for agricultural application

Chikosi, Gerald January 2014 (has links)
With the world's population expected to reach nine billion by 2050, agricultural production will have to double to meet this growing demand. Hence, a need for better infrastructure to enhance farming efficiency becomes apparent. There are a number of solutions that have been developed to date that are commercially available. They range from genetically modified seeds and bio/green fertilizers to advanced farming machinery amongst others. However most of the farming equipment developed has drawbacks such as: heavy weight – this leads to reduced yields due to soil compacting; human dependency – constant monitoring and controlling is needed; light dependency – excludes usage during the night or when visibility is poor. Therefore, a possible solution will be researched to enhance the evolution of farming equipment. Furthermore, a model will be developed for testing and verifying the research.
32

AN AUTOMATED ANCHORING SYSTEM FOR AN UNMANNED SURFACE VEHICLE

Unknown Date (has links)
The goal of this thesis is to simulate, design and build an automated device that allows unmanned vessels to anchor themselves in specified locations while being United States Coast Guard Navigation Rules compliant. This is a part of a larger project funded by the U.S. Department of Energy for Florida Atlantic University to build an unmanned platform with an Undershot Water Wheel on it. By simulating the environment of the South Florida Intercoastal Water Ways, forces acting on the line, anchor and the vessel are analyzed. These forces are used as the guide for the design and build of a line locking mechanism that takes the tension off the winch and a sensor package to monitor the environment the platform is in as well as control of the system. Based off experimental testing, the system was successful in handling all emulated environments with loads exceeding 150lbs of tension. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection
33

Ota-quadrotor: An Object-tracking Autonomous Quadrotor for Real-time Detection and Recognition

Coelho, Gavin 05 1900 (has links)
The field of robotics and mechatronics is advancing at an ever-increasing rate and we are starting to see robots making the transition from the factories to the workplace and homes as cost is reduced and they become more useful. In recent years quadrotors have become a popular unmanned air vehicle (UAV) platform. These UAVs or micro air vehicles (MAV) are being used for many new and exciting applications such as aerial monitoring of wildlife, disaster sites, riots and protests. They are also being used in the film industry, as they are significantly cheaper means of getting aerial footage. While quadrotors are not extremely expensive a good system can cost in the range of $3000 - $8000 and thus too costly as a research platform for many. There are a number of cheaper open source platforms. The ArduCopter is under constant development, has the largest community and is inexpensive making it an ideal platform to work with. The goal of this thesis was to implement video processing on a ground control station allowing for the ArduCopter to track moving objects. This was achieved by using the OpenCV video-processing library to implement object tracking and the MAVLink communication protocol, available on the ArduCopter platform, for communication.
34

Autonomous Source Localization

Peterson, John Ryan 01 May 2020 (has links)
This work discusses the algorithms and implementation of a multi-robot system for locating radioactive sources. The estimation algorithm presented in this work is able to fuse measurements collected by γ-ray spectrometers carried by an unmanned aerial and unmanned ground vehicle into a single consistent estimate of the probability distribution over the position of a point source in an environment. By constructing a set of hypotheses on the position of the point source, this method converts a non-linear problem into many independent linear ones. Since the underlying model is probabilistic, candidate paths may be evaluated by their expected reduction in uncertainty, allowing the algorithm to select good paths for vehicles to take. An initial hardware test conducted at Savannah River National Laboratory served as a proof of concept and demonstrated that the algorithm successfully locates a radioactive source in the environment, and moves the vehicle to that location. This approach also demonstrated the capability to utilize radiation data collected from an unmanned aerial vehicle to aid the ground vehicle’s exploration. Subsequent numerical experiments characterized the performance of several reward functions and different exploration algorithms in scenarios covering a range of source strengths and region sizes. These experiments demonstrated the improved performance of planning-based algorithms over the myopic method initially tested in the hardware experiments. / Doctor of Philosophy / This work discusses the use of unmanned aerial and ground vehicles to autonomously locate radioactive materials. Using radiation detectors onboard each vehicle, they are commanded to search the environment using a method that incorporates measurements as they are collected. A mathematical model allows measurements taken from different vehicles in different positions to be combined together. This approach decreases the time required to locate sources by using previously collected measurements to improve the quality of later measurements. This approach also provides a best estimate of the location of a source as data is collected. This algorithm was tested in an experiment conducted at Savannah River National Laboratory. Further numerical experiments were conducted testing different reward functions and exploration algorithms.
35

Future Autonomous Load Carriers : Conceptual Design and Development

Nagaraja, Rakesh, Kamatham, Karthik January 2020 (has links)
This report concerns the concept development of an autonomous load carrier whichneeds to be integrated with the autonomous truck NXT. The main purpose of thethesis is to develop a load carrier which can be used during off peak times with theautonomous truck which reduces the traffic, pollution and congestion in cities.Toachieve this a lot of pre- study in terms of research and survey is conducted on thetopics which are going to be used during the course of the thesis. The problemswhich were investigated during the thesis are the problems related to goods loadingand unloading from the warehouse to the truck and from the truck to the customer.To bridge the gap between these two processes an autonomous load carrier is thesolution. The product development methodology used by Ulrich and Eppinger [1] isused in this thesis. The findings from the pre-study was the need and type of the loadcarrier needed by the customers. Based on the requirements the concepts for the loadcarrier is developed and brainstormed. After the brainstorming process a concept isfinalised and a system level design of the concept is designed and presented in thethesis. The concept is designed to load and unload roll cages and pallets carryingfood products as the goods as it is one of the busy and essential services beingtransported today. The concept is made to be compact, safe, affordable, strong forit be integrated to the autonomous truck. The dimensions and specifications of theload carrier are approximated based on the study and research.
36

Autonomous Prototype of a Full Dimension Continuous Haulage System

Wells, Bruce 13 August 1999 (has links)
Design and development of a 1/10 scale prototype of a Full Dimension Continuous Haulage System manufactured by the Long-Airdox Company. The prototype, which will allow development and testing of path-planning and control algorithms for autonomous navigation and operation in underground coal mines, has been completed. The prototype system, though not an identical copy, clones all full-scale model degrees of freedom and functions necessary for navigation. In addition to the physical structure, a microcontroller-based system was developed for providing the necessary low-level motor controls, data gathering and multiple processor communications. High level software running on a laptop PC with the windows operating system is used for analyzing all measurement data, execution of path-planning and control algorithms and issuing the command data. / Master of Science
37

Range-Based Autonomous Underwater Vehicle Navigation Expressed in Geodetic Coordinates

Jabari, Rami Steve 23 June 2016 (has links)
Unlike many terrestrial applications, GPS is unavailable to autonomous underwater vehicles (AUVs) while submerged due to the rapid attenuation of radio frequency signals in seawater. Underwater vehicles often use other navigation technologies. This thesis describes a range-based acoustic navigation system that utilizes range measurements from a single moving transponder with a known location to estimate the position of an AUV in geodetic coordinates. Additionally, the navigation system simultaneously estimates the currents acting on the AUV. Thus the navigation system can be used in locations where currents are unknown. The main contribution of this work is the implementation of a range-based navigation system in geodetic coordinates for an AUV. This range-based navigation system is implemented in the World Geodetic System 1984 (WGS 84) coordinate reference system. The navigation system is not restricted to the WGS 84 ellipsoid and can be applied to any reference ellipsoid. This thesis documents the formulation of the navigation system in geodetic coordinates. Experimental data gathered in Claytor Lake, VA, and the Chesapeake Bay is presented. / Master of Science
38

Experimental Evaluation of Viscous Hydrodynamic Force Models for Autonomous Underwater Vehicles

McCarter, Brian Raymond 04 September 2014 (has links)
A comparison of viscous hydrodynamic force models is presented, with application on an autonomous underwater vehicle (AUV). The models considered here are \emph{quasi-steady}, meaning that force is expressed as a function of instantaneous vehicle state. This is in contrast to physical reality, where the force applied to a rigid body moving through a viscous fluid is history-dependent. As a result, the comparison of models is restricted to how well they are able to recreate a force history, rather than how closely they represent the underlying physics. Of the models under consideration, no single model performs significantly better than the others, but several perform worse. Each viscous hydrodynamic force model presented here is expressed as a linear combination of basis functions, which are nonlinear functions of body-relative velocity. The greater dynamical model is presented in a rigid-body framework with six degrees of freedom, with terms which account for inviscid fluid flow, restoring forces due to gravity, and control forces due to actuator motion. The models are selected from several that have been proposed in the literature, which include empirically-derived and physics-based models. Some models assume that the relationship between force and velocity is fundamentally linear or quadratic in nature, or make assumptions about coupled motion. The models are compared by their relative complexities, and also by their ability to reproduce data sets generated from field experiments. The complete dynamical equations are presented for each model, including coefficients suitable for use with the Virginia Tech 690 AUV. / Master of Science
39

Development of a Novel Zero-Turn-Radius Autonomous Vehicle

Haynie, Charles Dean 10 August 1998 (has links)
This thesis describes the development of a new zero-turn-radius (ZTR) differentially driven robotic vehicle hereinafter referred to as NEVEL. The primary objective of this work was to develop a device that could be used as a test-bed for continued autonomous vehicle research at Virginia Tech while meeting the entry requirements of the Annual International Unmanned Ground Robotics Competition. In developing NEVEL, consideration was given to the vehicle's mechanical and electrical design, sensing and computing systems, and navigation strategy. Each of these areas was addressed individually, but always within the context of optimal integration to produce the best overall vehicle system. A constraint that directed much of the design process was the desire to integrate industrially available and proven components rather than creating custom designed systems. This thesis also includes a review of the relevant literature as it pertains to both subsystem and overall vehicle design. NEVEL, the vehicle that was created from this research effort, is novel in several respects. It is one of the few true embodiments of a fully functioning, three-wheel, differential drive autonomous vehicle. Several previous studies have developed this concept for indoor applications, but none has resulted in a working test-bed that can be applied to an unstructured, outdoor environment. NEVEL also appears to be one of the few autonomous vehicle systems to fully incorporate a commercially available laser range finder. These features alone would make NEVEL a useful platform for continued research. In addition, however, by using common, off-the-shelf components and a personal computer platform for all computation and control, NEVEL has been created to facilitate testing of new navigation and control strategies. As testimony to the success of this design, NEVEL was recognized at the Sixth Annual International Unmanned Ground Robotics Competition as the best overall design. / Master of Science
40

Vision Based Localization of Drones in a GPS Denied Environment

Chadha, Abhimanyu 01 September 2020 (has links)
In this thesis, we build a robust end-to-end pipeline for the localization of multiple drones in a GPS-denied environment. This pipeline would help us with cooperative formation control, autonomous delivery, search and rescue operations etc. To achieve this we integrate a custom trained YOLO (You Only Look Once) object detection network, for drones, with the ZED2 stereo camera system. With the help of this sensor we obtain a relative vector from the left camera to that drone. After calibrating it from the left camera to that drone's center of mass, we then estimate the location of all the drones in the leader drone's frame of reference. We do this by solving the localization problem with least squares estimation and thus acquire the location of the follower drone's in the leader drone's frame of reference. We present the results with the stereo camera system followed by simulations run in AirSim to verify the precision of our pipeline. / Master of Science / In the recent years, technologies like Deep Learning and Machine Learning have seen many rapid developments. This has lead to the rise of fields such as autonomous drones and their application in fields such as bridge inspection, search and rescue operations, disaster management relief, agriculture, real estate etc. Since GPS is a highly unreliable sensor, we need an alternate method to be able to localize the drones in various environments in real time. In this thesis, we integrate a robust drone detection neural network with a camera which estimates the location. We then use this data to get the relative location of all the follower drones from the leader drone. We run experiments with the camera and in a simulator to show the accuracy of our results.

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