Kick control: using the attracting states arising within the sensorimotor loop of self-organized robots as motor primitives

Self-organized robots may develop attracting states within the sensorimotor loop, that is within the phase space of neural activity, body, and environmental variables. Fixpoints, limit cycles, and chaotic attractors correspond in this setting to a non-moving robot, to directed, and to irregular locomotion respectively. Short higher-order control commands may hence be used to kick the system from one self-organized attractor robustly into the basin of attraction of a different attractor, a concept termed here as kick control. The individual sensorimotor states serve in this context as highly compliant motor primitives. We study different implementations of kick control for the case of simulated and real-world wheeled robots, for which the dynamics of the distinct wheels is generated independently by local feedback loops. The feedback loops are mediated by rate-encoding neurons disposing exclusively of propriosensoric inputs in terms of projections of the actual rotational angle of the wheel. The changes of the neural activity are then transmitted into a rotational motion by a simulated transmission rod akin to the transmission rods used for steam locomotives. We find that the self-organized attractor landscape may be morphed both by higher-level control signals, in the spirit of kick control, and by interacting with the environment. Bumping against a wall destroys the limit cycle corresponding to forward motion, with the consequence that the dynamical variables are then attracted in phase space by the limit cycle corresponding to backward moving. The robot, which does not dispose of any distance or contact sensors, hence reverses direction autonomously.Comment: 17 pages, 9 figure

An overview of a Lagrangian method for analysis of animal wake dynamics

The fluid dynamic analysis of animal wakes is becoming increasingly popular in studies of animal swimming and flying, due in part to the development of quantitative flow visualization techniques such as digital particle imaging velocimetry (DPIV). In most studies, quasi-steady flow is assumed and the flow analysis is based on velocity and/or vorticity fields measured at a single time instant during the stroke cycle. The assumption of quasi-steady flow leads to neglect of unsteady (time-dependent) wake vortex added-mass effects, which can contribute significantly to the instantaneous locomotive forces. In this paper we review a Lagrangian approach recently introduced to determine unsteady wake vortex structure by tracking the trajectories of individual fluid particles in the flow, rather than by analyzing the velocity/vorticity fields at fixed locations and single instants in time as in the Eulerian perspective. Once the momentum of the wake vortex and its added mass are determined, the corresponding unsteady locomotive forces can be quantified. Unlike previous studies that estimated the time-averaged forces over the stroke cycle, this approach enables study of how instantaneous locomotive forces evolve over time. The utility of this method for analyses of DPIV velocity measurements is explored, with the goal of demonstrating its applicability to data that are typically available to investigators studying animal swimming and flying. The methods are equally applicable to computational fluid dynamics studies where velocity field calculations are available

Machine learning and its applications in reliability analysis systems

In this thesis, we are interested in exploring some aspects of Machine Learning (ML) and its application in the Reliability Analysis systems (RAs). We begin by investigating some ML paradigms and their- techniques, go on to discuss the possible applications of ML in improving RAs performance, and lastly give guidelines of the architecture of learning RAs. Our survey of ML covers both levels of Neural Network learning and Symbolic learning. In symbolic process learning, five types of learning and their applications are discussed: rote learning, learning from instruction, learning from analogy, learning from examples, and learning from observation and discovery. The Reliability Analysis systems (RAs) presented in this thesis are mainly designed for maintaining plant safety supported by two functions: risk analysis function, i.e., failure mode effect analysis (FMEA) ; and diagnosis function, i.e., real-time fault location (RTFL). Three approaches have been discussed in creating the RAs. According to the result of our survey, we suggest currently the best design of RAs is to embed model-based RAs, i.e., MORA (as software) in a neural network based computer system (as hardware). However, there are still some improvement which can be made through the applications of Machine Learning. By implanting the 'learning element', the MORA will become learning MORA (La MORA) system, a learning Reliability Analysis system with the power of automatic knowledge acquisition and inconsistency checking, and more. To conclude our thesis, we propose an architecture of La MORA

New applications for phosphoric acid fuel cells

New applications for phosphoric acid fuel cells were identified and evaluated. Candidates considered included all possibilities except grid connected electric utility applications, on site total energy systems, industrial cogeneration, opportunistic use of waste hydrogen, space and military applications, and applications smaller than 10 kW. Applications identified were screened, with the most promising subjected to technical and economic evaluation using a fuel cell and conventional power system data base developed in the study. The most promising applications appear to be the underground mine locomotive and the railroad locomotive. Also interesting are power for robotic submersibles and Arctic villages. The mine locomotive is particularly attractive since it is expected that the fuel cell could command a very high price and still be competitive with the conventionally used battery system. The railroad locomotive's attractiveness results from the (smaller) premium price which the fuel cell could command over the conventional diesel electric system based on its superior fuel efficiency, and on the large size of this market and the accompanying opportunities for manufacturing economy

Local Agenda 21 and ecological urban restructuring: An European model project in Leipzig

AGENDA 21 as one of the final resolutions of the UN Conference on Environment and Development (UNCED) in June 1992 in Rio de Janeiro stresses in chapter 28 the important role of cities, towns and communities in globally sustainable development. One of the most important European model projects in this respect was carried out in Leipzig from 1993 to 1997. The Leipzig Ostraum Project was supported through the LIFE support program of the European Union with the largest subsidy awarded till that time (4,3 mill. DM, with a total project budget of about 20 mill. DM). The central goal of this project is the use, testing and further development of present knowledge with regard to sustainable urban restructuring in combination with innovative strategies of economic and employment policies. The scope of traditional urban ecology is extended to comprise adjacent rural areas and to revitalize regional material flows. In the meantime, affiliated projects have won support by the THERMIE program of the European Union and the EXWOST-program of the German Federal Ministry of Construction. This paper reports on the most important results of the Leipzig Project to date. In particular, the authors show that the concept of ecological urban restructuring and the Local Agenda 21 are in harmony with one another and can play a decisive role in stimulating consensus on future urban development. All urban actors can be winners in this process. Difficulties arose, however, through dishonest use of financial support by the project agency. -- Die AGENDA 21, Abschlußdokument der UN-Konferenz über Umwelt und Entwicklung im Juni 1992 in Rio de Janeiro, betont in ihrem Kapitel 28 die Rolle der Kommunen, Städte und Gemeinden bei einer global zukunftsfähigen Entwickung (sustainable development). Eines der wichtigsten europäischen Modellprojekte zu diesem Thema wurde in den Jahren 1993 bis 1997 in Leipzig durchgeführt. Zentrale Zielstellung des mit der bisher höchsten Fördersumme aus dem LIFEProgramm der Europäischen Kommission (4,3 Mio DM bei einem Projektvolumen von knapp 20 Mio DM) geförderten Leipziger Ostraum-Projektes ist die Anwendung und Weiterentwicklung des Erkenntnisstandes zum Thema des zukunftsfähigen Städtebaus in Kombination mit innovativen Strategien einer ökologischen Wirtschafts- und Beschäftigungspolitik. Die traditionelle Stadtökologie wird erweitert durch die Einbeziehung der Umlandgemeinden und die Revitalisierung regionaler Stoffkreisläufe. Inzwischen sind ergänzende Tochterprojekte mit Förderung aus dem THERMIE-Programm der Europäischen Kommission und dem EXWOST-Programm des Bundesbauministeriums eingeworben werden. In dem Paper wird über die wichtigsten bisherigen Ergebnisse des Projektes berichtet. Insbesondere wird gezeigt, daß die Konzepte des Ökologischen Stadtumbaus und der Lokalen Agenda 21 miteinander harmonieren und eine konsensstiftende Funktion in der zukünftigen Stadtentwicklung übernehmen können. Alle städtischen Akteure können Winner in diesem Prozeß sein. Durch unredlichen Umgang des Projektträgers mit den Fördergeldern war das Leipziger Projekt in jüngster Zeit allerdings in Schwierigkeiten geraten.