Analysis and synthesis of collective motion: from geometry to dynamics

The subject of this dissertation is collective motion, the coordinated motion of two or more individuals, in three-dimensional space. Inspired by the problems of understanding collective motion in nature and designing artificial collectives that can produce complex behaviors, we introduce mathematical methods for the analysis of collective motion data, and biologically-inspired algorithms for generating collective motion in engineered systems. We explore two complementary approaches to the analysis and synthesis of collective motion. The first "top-down" approach consists in exploiting the geometry of n-body systems to identify certain elementary components of collective motion. A main contribution of this thesis is to reveal a new geometrical structure (fiber bundle) of the translation-reduced configuration space and a corresponding classification of collective motions alternative to the classical one based on reduction to shape space. We derive a mathematical framework for decomposing arbitrary collective motions into elementary components, which can help identify the main modes of an observed collective phenomenon. We synthesize vector fields that implement some of the most interesting elementary collective motions, and suggest, whenever feasible, decentralized implementations. The second "bottom-up" approach consists in starting from known biologically-plausible individual control laws and exploring how they can be used to generate collective behaviors. This approach is illustrated using the motion camouflage proportional guidance law as a building block. We show that rich and coordinated motion patterns can be obtained when two individuals are engaged in mutual pursuit with this control law. An extension of these dynamics yields coordinated motion for a collective of n individuals

Stability Analysis of Plates and Shells

This special publication contains the papers presented at the special sessions honoring Dr. Manuel Stein during the 38th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference held in Kissimmee, Florida, Apdl 7-10, 1997. This volume, and the SDM special sessions, are dedicated to the memory of Dr. Manuel Stein, a major pioneer in structural mechanics, plate and shell buckling, and composite structures. Many of the papers presented are the work of Manny's colleagues and co-workers and are a result, directly or indirectly, of his influence. Dr. Stein earned his Ph.D. in Engineering Mechanics from Virginia Polytechnic Institute and State University in 1958. He worked in the Structural Mechanics Branch at the NASA Langley Research Center from 1943 until 1989. Following his retirement, Dr. Stein continued his involvement with NASA as a Distinguished Research Associate

Vehicle and Traffic Safety

The book is devoted to contemporary issues regarding the safety of motor vehicles and road traffic. It presents the achievements of scientists, specialists, and industry representatives in the following selected areas of road transport safety and automotive engineering: active and passive vehicle safety, vehicle dynamics and stability, testing of vehicles (and their assemblies), including electric cars as well as autonomous vehicles. Selected issues from the area of accident analysis and reconstruction are discussed. The impact on road safety of aspects such as traffic control systems, road infrastructure, and human factors is also considered

NASA Geodynamics Program

Activities and achievements for the period of May 1983 to May 1984 for the NASA geodynamics program are summarized. Abstracts of papers presented at the Conference are inlcuded. Current publications associated with the NASA Geodynamics Program are listed

Toward a Framework for Systematically Categorizing Future UAS Threat Space

Title from PDF of title page, viewed September 21, 2022Dissertation advisor: Travis FieldsVitaIncludes bibliographical references (pages 241-270)Dissertation (Ph.D.)--Department of Civil and Mechanical Engineering, Department of Electrical and Computer Engineering. University of Missouri--Kansas City, 2021The development of unmanned aerial vehicles (UAVs) is occurring as fast or faster than any other innovation throughout the course of human history. Building an effective means of defending against threats posed by malicious applications of novel technology is imperative in the current global landscape. Gone are the days where the enemy and the threat it poses are well defined and understood. Defensive technologies have to be modular and able to adapt to a threat technology space which is likely to recycle several times over during the course of a single defense system acquisition cycle. This manuscript wrestles with understanding the unique threat posed by UAVs and related technologies. A thorough taxonomy of the problem is given including projections for how the defining characteristics of the problem are likely to change and grow in the near future. Next, a discussion of the importance of tactics related to the problem of a rapidly changing threat space is provided. A discussion of case studies related to lessons learned from military acquisition programs and pivotal technological innovations in the course of history are given. Multiple measures of success are proposed which are designed to allow for meaningful comparisons and honest evaluations of capabilities. These measures are designed to facilitate discussions by providing a common, and comprehensible language that accounts for the vast complexity of the problem space without getting bogged down by the details. Lastly, predictions for the future threat space comprising UAVs is given. The contributions of this work are thus threefold. Firstly, an analytic framework is presented including a detailed parameterization of the problem as well as various solution techniques borrowed from a variety of fields. Secondly, measures of success are presented which attempt to compare the effectiveness of various systems by converting to expected values in terms of effective range, or extending the popular concept of kill chain and collapsing effectiveness into units of time. A novel technique for measuring effectiveness is presented whereby effectiveness is composed of various individual probabilities. Probabilities and associated distributions can be combined according to the rules of joint probabilities and distributions and allows performance against a probabilistic threat to be measured succinctly and effectively. The third contribution concerns predictions made with respect to the UAS threat space in the future. These predictions are designed to allow for defensive systems to be developed with a high expected effectiveness against current and future threats. Essentially this work comprises a first attempt toward developing a complete framework related to engagement and mission level modeling of a generic defensive system (or combination of systems) in the face of current and future threats presented by UAS.Introduction -- Literature review -- War gaming -- Measures of success -- Conclusion

The performance of hybrid GPS and GLONASS

In recent years, the market served by satellite positioning systems has expanded exponentially. It is stimulated by the needs of an ever increasing number and variety of scientific, business and leisure applications. The dominant system is the USA's GPS, or Global Positioning System. However, GPS is not a panacea for all positioning tasks, in any environmental situation. For example, two of the fastest growing applications, vehicle tracking and personal location, operate in an often harsh signal reception environment. This can be so severe that even with the current 29 working satellites, GPS may struggle to perform. In exceptional circumstances it can fail to provide a positioning service at all. The simplest way to improve the situation when signal reception is poor, is to add similar signals from alternative satellite systems. This has already been achieved by combining GPS with the Russian satellite positioning system, Global'naya Navigatsionnaya Sputnikova Sistema, abbreviated to GLONASS. The combination of GPS with GLONASS is referred to here as Hybrid. But how good is Hybrid relative to GPS, and how can performance be evaluated objectively? The research project presented here set out to answer this question, and to understand the situations in which Hybrid failed, and ask what solutions were then available to fulfil a positioning task. The problems associated with integrating one satellite positioning system with another, their potential inconsistencies and their impact on positioning errors were also examined. This field of research is relevant to Hybrid as defined here, and also to other mixed systems, for example GPS with EGNOS, a European geostationary satellite system, and GPS with Galileo, a proposed global system controlled by the Europeans. The issues were addressed from the viewpoint of practical usage of the positioning systems. Hence the many and varied experiments to quantify positioning performance using both static receivers, and a variety of platforms with wide ranging levels of vehicle dynamics. The capability of satellite positioning systems to work in the harshest environments, was tested in the proposed Olympic sport of bob skeleton. This involved the development of the acquisition system, and a number of programs. The latter were equally applicable to the ensuing work with road vehicles, and the quantitative assessment of positioning performance relative to a truth. The processes established to manipulate, import, and merge satellite based vehicle tracking data with Ordnance Survey digital mapping products, have already been used in four other projects within the School of Civil Engineering. The software to regularise positioning interval, smoothing processes, and to compare tracking data with a truth, have been similarly provided. Without major funding the outlook for GLONASS and hence Hybrid looks bleak, and it is predicted that without replenishment the constellation may fall to six satellites by the end of 2001. However as mentioned above, the issues identified, and ideas and software developed in this research, will be directly applicable to any future hybridisation of GPS with Galileo