Thesis (Ph. D.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 134-142). Also available on the World Wide Web.

Th. doct.-ing.--Besançon, 1984. N°: 8.

Boston University. University Professors Program Senior theses. / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / 2031-01-02

In the last decades, the quantity of robot applications has increased enormously in various areas of operation. Their advantages like automation and accuracy are interesting for health care, as well. Besides of surgery and patient transportation, robots can be used for therapy, too. This master thesis presents an analytical model of a hydraulic hexapod robot, which is intended to be used as a gait trainer in a rehabilitation application. In order to prove the model, a measurement of all actuators is performed. They prove the linear plant characteristic caused by an installed pressure compensator. Consequently, a suitable decoupled state space control and an observer are developed and simulated. Considering the velocity and the control effort, the feedforward linear-quadratic state space controller shows the best system performance. The tests permit a model simplification and exhibit the negligible influence of small loads. The potential of the hexapod robot has to be considered regarding the further development of the periphery. Doing so, the presented controller can be implemented and the robot can be used in many areas. / Tesis

Software bots are becoming increasingly pervasive in our everyday lives. While bots have been around for many decades, recent technological advancements and the adoption of language-based platforms have led to a surge of new ubiquitous software bots. Although many new bots are being built, the terminology used to describe them and their properties are vast, diverse, and often inconsistent. This hinders our ability to study, understand, and classify bots, and restricts our ability to help practitioners design and evaluate their bots. The overarching goal of this thesis is to provide a deeper understanding of the complexities of modern software bots. To achieve this, I reflect on a multitude of existing software bot definitions and classifications. Moreover, I propose an updated definition for bots and compare them to other bot-like technologies. As my main contribution, I formally define a set of consistent terminology for describing and classifying software bots, through the development of a faceted taxonomy of software bots. The taxonomy focuses on the observable properties and behaviours of software bots, abstracting details pertaining to their structure and implementation, to help safeguard against technological change. To bridge the gap between existing research and the proposed taxonomy, I map the terminology used in previous literature to the terminology used in the software bot taxonomy. Lastly, to make my contributions actionable, I provide guidelines to illustrate how the proposed taxonomy can be leveraged by researchers, practitioners, and users. / Graduate

This thesis is primarily concerned with motion control of robot manipulators with emphasis placed on adaptive impedance control and relevant computational issues. The general approach taken in our studies is a model-based approach, that is, the algorithms developed is based on the dynamic model of the robot(s) involved. Two computational formulations are derived for the evaluation of the so-called regressor dynamics of a robot manipulator, which has played a key role in the development of popular stable adaptive control algorithms for robot manipulators. The closed-form version of the formulations is based on the Lagrangian dynamics formulation while the recursive version is based on the Newton-Euler dynamics. As an application of the regressor dynamics formulation, the popular Slotine-Li adaptive control algorithm is modified and then implemented on a PUMA 560 robot. Satisfactory computational efficiency of the regressor formulas, especially the recursive formula, has been demonstrated in our experimental implementations. To extend adaptive position control algorithms to force control, the concept of target impedance reference trajectory is introduced which makes it possible to inject two stable adaptive position control algorithms into Hogan's conventional impedance control. These two adaptive impedance control algorithms have been shown stable. Simulation and real-time implementation of the algorithms on a PUMA 560 robot are reported. The last part of the thesis conducts a study on optimal load distribution and coordination of multiple robots. Optimal load distribution schemes using a p-norm type optimization approach are proposed. The algorithms are then adopted to dynamically link the two-level controllers in a proposed coordination framework. Simulation results are presented to show the performance of the proposed structure. / Graduate

Ingeniero Civil Mecánico / Las nuevas tecnologías de fabricación digital, permiten producir elementos complejos de manera rápida y eficiente. Una aplicación de estas tecnologías es el desarrollo de vehículos voladores no tripulados. En particular, en el último tiempo interesan los micro vehículos aéreos que se asemejan a los pequeños insectos debido a las ventajas que estos presentan. Estos últimos, entre las características que exhiben es una mayor maniobrabilidad y estabilidad, además que se pueden pilotar en lugares de difícil acceso o peligrosos para una persona. El objetivo de esta memoria es diseñar y construir un mecanismo inspirado en características biológicas de aves o insectos y estudiar perfiles de alas que presenten mejores propiedades aerodinámicas. Para lograr el objetivo se cuenta con diversas fuentes de financiamiento (Fondecyt, ANR-Conicyt, etc.), además de los equipos, software e impresoras de fabricación digital disponibles en el laboratorio de robótica del departamento de ingeniería mecánica de la Universidad de Chile. La metodología consiste en una etapa de recopilación de información y antecedentes relacionados con la aerodinámica, materiales y construcción de robots similares. Luego se diseñarán los distintos componentes mecánicos involucrados, poniendo principal énfasis en el diseño y construcción de las alas del vehículo. Se estudiaron dos perfiles de alas para determinar cual presenta mejores propiedades aerodinámicas. Se midieron experimentalmente el empuje y sustentación que son capaces de generar y se modificaron parámetros en el diseño que influyen en la flexión y torsión de las alas para medir como estos afectan en su desempeño. Se midió en un túnel de viento la sustentación que genera el paso del aire a través de las alas para distintas velocidades de circulación del viento. Con el sistema mecánico definitivo, se realizaron pruebas de vuelo para estudiar la capacidad de vuelo del MAV. Se traslado el centro de masa y el ángulo de ataque de las alas para lograr condiciones de vuelo mas estables. Finalmente se construyó un micro vehículo aéreo el cual logro volar por unos instantes, pero que no fue capaz de mantener un vuelo estable.

M.Ing. / The objective of this research is to present motion planning methods for an autonomous robot. Motion planning is one of the most important issues in robotics. The goal of motion planning is to find a path from a starting position to a goal position while avoiding obstacles in the environment. The robot's environment can be static or dynamic. Motion planning problems can be addressed using either classical approaches or obstacle-avoidance approaches. The classical approaches discussed in this work are: Voronoi, Visibility graph, Cell decomposition and Potential field. The obstacle avoidance approaches discussed in this research are: Neural network, Bug Algorithms, Dynamic Window Approach, Vector field histogram, Bubble band technique and Curvature velocity techniques. In this dissertation, simulation results and experimental results are presented. In the simulation, we address the motion planning issues using points extracted from a map. Algorithms used for simulation are: Voronoi algorithm, Hopfield neural network, Potential field and A* search algorithm. The simulation results show that the approaches used are effective and can be applied to real robots to solve motion planning problems. In the experiment, the Dynamic Window Approach (DWA) is used for obstacle-avoidance, a Pioneer robot explores the environment using an open source system, ROS (Robot Operating System). The experiment proved that DWA can be used to avoid obstacles in real time. keywords Motion planning, autonomous robot, optimal path problems, environment, search algorithm, classical approaches, obstacle avoidance approaches, exploration.

The history of the robot as a concept and as a fact is indicated, and the current linguistic approach to robotology discussed. The problem of designing a robot-controller is approached by taking a simplified, computer-simulated, model of a robot in an environment, and writing programs to enable the robot to move around its environment in a reasonably intelligent manner. The problems of concept representation and the creation and execution of plans are dealt with in this simple system, and the problem of exploration is encountered but not satisfactorily dealt with. The robots' environment consists of a rectangular grid in which squares are labelled as belonging to the boundary, to fixed or movable objects, or to holes, while the robot itself occupies a single square, can sense the labels of the eight surrounding squares, can turn, and can pickup, move, and drop movable objects. The boundary of a typical environment is thus a rectanguloid polygon, which can be compared to the floor-plan of a one-level house. After an initial exploration the basic representation of the environment is as a sequence of edge-lengths and turns, called the ring-representation. An algorithm is described which produces the set of maximal subrectangles of the environment (i.e. rooms, passages, doorways) from the ring representation. To make plans for moving within the environment, the robot first views the maximal subrectangles as the vertices of a graph, wherein two vertices are connected by an edge if and only if the corresponding maximal subrectangles overlap, and then uses a path-finding algorithm to find a path between two vertices of the graph. This path constitutes a "plan of action". Whenever an isolated object or hole is found, its ring-representation is generated and its set of maximal subrectangles produced. Thus the shapes of objects and holes within the environment can be compared in various ways. In particular, an algorithm is described which compares the shape of a movable object with that of a hole to ascertain if the movable object could be moved to fit inside the hole without "physically" moving the object. ROSS, an interactive computer program which simulates the robot-environment model, is described. A command language allows the user to specify tasks for the robot at various conceptual levels. Several problems are listed concerning the ways in which a robot might explore, represent, and make plans about, its environment, most of which are amenable to direct attack in this simplified model. Finally, theoretical questions concerning two-dimensional rectanguloid shapes are raised. / Science, Faculty of / Computer Science, Department of / Graduate

The equations of motion describing a robot's dynamics are coupled and nonlinear, making the design of an optimum controller difficult using classical techniques. In this work an explicit adaptive control law is proposed based on a discrete linear model for each link and on the minimization of a quadratic performance criterion. The system parameters are recursively estimated at each control step using least squares. A computer simulation of the resulting scheme is performed to evaluate the controller. The simulation model is based on the first three links of an existing robot, includes motor dynamics and treats the wrist assembly as a load mass. Simulated test paths requiring movement of the outer two links indicate that the controller adapts and that its behaviour is stable and convergent. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate