Dexterous Robotic Hands: Kinematics and Control

This report presents issues relating to the kinematics and control of dexterous robotic hands using the Utah-MIT hand as an illustrative example. The emphasis throughout is on the actual implementation and testing of the theoretical concepts presented. The kinematics of such hands is interesting and complicated owing to the large number of degrees of freedom involved. The implementation of position and force control algorithms on such tendon driven hands has previously suffered from inefficient formulations and a lack of sophisticated computer hardware. Both these problems are addressed in this report. A multiprocessor architecture has been built with high performance microcomputers on which real-time algorithms can be efficiently implemented. A large software library has also been built to facilitate flexible software development on this architecture. The position and force control algorithms described herein have been implemented and tested on this hardware.

Contact Sensors for Dexterous Robotic Hands

This thesis examines a tactile sensor and a thermal sensor for use with the Utah-MIT dexterous four fingered hand. Sensory feedback is critical or full utilization of its advanced manipulatory capabilities. The hand itself provides tendon tensions and joint angles information. However, planned control algorithms require more information than these sources can provide. The tactile sensor utilizes capacitive transduction with a novel design based entirely on silicone elastomers. It provides an 8 x 8 array of force cells with 1.9 mm center-to-center spacing. A pressure resolution of 8 significant bits is available over a 0 to 200 grams per square mm range. The thermal sensor measures a material's heat conductivity by radiating heat into an object and measuring the resulting temperature variations. This sensor has a 4 x 4 array of temperature cells with 3.5 mm center-to-center spacing. Experiments show that the thermal sensor can discriminate among material by detecting differences in their thermal conduction properties. Both sensors meet the stringent mounting requirements posed by the Utah-MIT hand. Combining them together to form a sensor with both tactile and thermal capabilities will ultimately be possible. The computational requirements for controlling a sensor equipped dexterous hand are severe. Conventional single processor computers do not provide adequate performance. To overcome these difficulties, a computational architecture based on interconnecting high performance microcomputers and a set of software primitives tailored for sensor driven control has been proposed. The system has been implemented and tested on the Utah-MIT hand. The hand, equipped with tactile and thermal sensors and controlled by its computational architecture, is one of the most advanced robotic manipulatory devices available worldwide. Other ongoing projects will exploit these tools and allow the hand to perform tasks that exceed the capabilities of current generation robots.

New algorithms for synthesized design of optical filters

Chebyshev optical-filter algorithms for low-cost microcomputers have been improved. An offset ripple is now used for better transmission/matching in low-pass stacks. A prototype for narrowband filters is now more general and nearer practicability.

Multi-microprocessor control of processes with pure time delay

In 1967 a novel scheme was proposed for controlling processes with large pure time delay (Fellgett et al, 1967) and some of the constituent parts of the scheme were investigated (Swann, 1970; Atkinson et al, 1973). At that time the available computational facilities were inadequate for the scheme to be implemented practically, but with the advent of modern microcomputers the scheme becomes feasible. This paper describes recent work (Mitchell, 1987) in implementing the scheme in a new multi-microprocessor configuration and shows the improved performance it provides compared with conventional three-term controllers.

The ethics of the hacker taggers : the new generation of hackers

In the contemporary world, the latter interpretation is by far the more common (although persons belonging to the former category of hacker would seek to more accurately define the latter group, particularly those with a malicious intent, as ‘crackers’). Hackers are by no means a new threat and have routinely featured in news stories during the last two decades. Indeed, they have become the traditional ‘target’ of the media, with the standard approach being to present the image of either a ‘teenage whiz kid’ or an insidious threat. In reality, it can be argued that there are different degrees of the problem.
Donn Parker (Parker, 1976) highlighted that the individuals involved in computer crime in the 1960’s and 1970’s were employed as key punch operators or clerks in EDP organisations and the crimes were crimes of opportunity. In the 1980’s with the development of cheaper home microcomputers and modems, a new generation of younger computer users emerged. One of the features of this younger group was a keen interest in the technologies that lead to the development of hackers.

Development of a new versatile computer controlled electrochemical/ESR data acquisition system

A new versatile computer controlled electrochemlcal/ESR data acquisition system has been developed for the Investigation of short-lived radicals with life-times of 20 milliseconds and greater, Different computer programs have been developed to monitor the decay of radicals; over hours or minutes, seconds or milliseconds. Signal averaging and Fourier smoothing is employed in order to improve the signal to noise ratio. Two microcomputers are used to control the system, one home-made computer containing the M6800 chip which controls the magnetic field, and an IBM PC XT which controls the electrochemistry and the data acquisition. The computer programs are written in Fortran and C, and call machine language subroutines, The system functions by having the radical generated by an electrochemical pulse: after or during the pulse the ESR data are collected. Decaying radicals which have half-lives of seconds or greater have their spectra collected in the magnetic field domain, which can be swept as fast as 200 Gauss per second. The decay of the radicals in the millisecond region is monitored by time-resolved ESR: a technique in which data is collected in both the time domain and in the magnetic field domain. Previously, time-resolved ESR has been used (without field modulation) to investigate ultra-short-lived species with life-times in the region of only a few microseconds. The application of the data acquisition system to chemical systems is illustrated. This is the first time a computer controlled system whereby the radical is generated by electrochemical means and subsequently the ESR data collected, has been developed.

Teenage technological experts : Bourdieu and the performance of expertise

This thesis explores the construction of technological expertise amongst a heterogenous group of New Zealand teenagers, specifically in regard to their home computer use, which for many of them is their primary site of leisure. This thesis explores the field in which these teenagers are positioned, and explains the practice constituting that field. In this field, the trajectories towards expertise are explained including the time, experimentation, and pleasure evident in their praxis. The qualitative study involved observations and interviews with eight teenagers aged 13 – 17. Five boys and three girls participated and each attended one of various secondary schools located within a provincial city in New Zealand. All of the participants considered themselves to be technological experts, and their peers and/or their family supported this comprehension. Drawing on Pierre Bourdieu’s socio-cultural theories, the capital (cultural, economic, social) and habitus of the teenagers are described (habitus being what makes them who they are, and continues to define who they are in the future). Chapter five centres on explaining the field the teenagers have positioned themselves in, namely the field of out-of-school leisure and home computer use. It also explores the construction and performance of technological expertise within the field. Chapter six examines traditional views of schooling and expertise, and contrasts these views with what the teenagers think about their learning and expertise. This gap is specifically explained with regard to differences between the concepts and value of learning, expertise, and technology, and how they are recognised and valued differently between generations. Chapter seven explores the praxis that the participants exhibit, which is arguably misrecognized by those whose interests are in the established order (e.g. institutional, societal structures). The field they are placed in is arguably part of the broader field of education, yet the findings suggest their capital is misrecognized by digital newcomers, and therefore not legitimated. This thesis concludes that the gap between teenager and adult understandings of expertise is exacerbated in the digital world in which the teenagers position themselves. Their schooling is mainly positioned in the print culture of previous generations and consequently, in the lives of these teenagers, schooling has had little influence on the development of their technological expertise. Additionally, gender has had little impact in their development of expertise; therefore stereotypical notions of female underachievement as computer experts are contested.

Case study of electronic networking in an initial teacher education course

Electronic networking ('computer-mediated communication1), considered to be ‘unique domain for educational activity’ (Harasim, 1989:50) and ‘new educational paradigm’ (Mason & Kaye, 1989:23), has been widely used and researched in K-12 schooling, place-based undergraduate subjects and distance education courses. However, only a limited number of reports of usage with experienced teachers (professional development), beginning teachers (induction support) and trainee teachers (initial training) have been published. Hence, little is known about the ways in which this new medium might contribute to the acquisition and maintenance of professional knowledge in the field of teacher education. The purpose of this study was to document an application of electronic networking in an initial 'school-based1 teacher education course. Three factors which were considered to be important in the adoption of electronic networking were specifically addressed: (a) the potential of the medium to attract and maintain a representative and comprehensive audience', (b) the willingness of participants to use the medium for the notation of ideas about teaching; and, (c) the extent to which reflection on practice was evident in network messages. This study also identified and investigated other effects which emerged as participants attempted to negotiate personal relationships with new technology. A case study was selected to investigate audience, notation, reflection, and other effects, in a particular application. Data were collected using participant observation, software-generated statistics, printed documentation, university records, questionnaires, interviews and content analysis of messages. These data were used to describe and analyse network participation by trainee teachers, classroom teachers and university staff. The data revealed that an audience did exist on the electronic network but that this was not comprehensive. Teachers had difficulty accessing the network because of other school commitments, access to equipment and personal competence with microcomputers. These difficulties indicated that developing and maintaining the teacher audience may be a major problem with electronic networking in initial teacher education. This case study revealed that deeply held concerns about notation of ideas by trainee teachers and classroom teachers can be powerful reasons for limited network participation. For trainee teachers, recording ideas publicly presented special difficulties associated with written communication. They were concerned about writing for an audience; about what to write about and how to write it. The loss of visual and verbal cues which form part of face-to-face communication was also a problem leading to concerns about how messages would be received by others. However, the overwhelming concern of almost all trainee teachers about presenting their own ideas was Tear of criticism' from peers (in particular), and other participants on the network. Trainee teachers expressed concerns about the 'dangers' of putting their thoughts in writing, the scrutiny their messages might have received from others, and the public 'criticism' about what they wrote which might have appeared on the network. Knowing that messages were stored on the network, and could be retrieved at some later date, heightened anxiety about the vulnerability of written communication; what was written on one occasion may have to be defended at some later date when the views expressed initially were no longer held. Classroom teachers were also unsure about recording their own ideas in an electronic form. Like trainee teachers, they were concerned about the scrutiny their contributions might receive from other users, and the lack of visual and verbal cues which they had learnt to use in face-to-face communication. Notating ideas in text-based messages which were archived (by the software), and retrievable by others later, was also daunting to many teachers. Another major 'danger' for teachers was the possible repercussions of 'public comment' about curriculum policy and initiatives which they thought might get them into 'trouble' with their employer. Since very few messages were contributed to conferences, there was little evidence of reflection in network communication. In the main, the network was not used to share information and ideas about curriculum and teaching. Public examples of collaboration between participants were not evident, and the 'special knowledge' held by members in each distinct group of users was not elaborated and discussed. Messages were not used to request information or clarification about issues, to outline the processes by which decisions about teaching were reached, or to synthesis ideas from different sources. The potential of the medium to operationalise reflective practice was not realised. Among the effects observed, the use of an anonymous account to access the network, and the impact this had on participation (in one conference) was considered to be a particularly significant finding. While the opportunity to systematically investigate the effects of anonymity on network participation and message contributions was not realised (by the author) while the research was in progress, the effects observed and discussed are considered to be important and worthy of further investigation. In this case study, the anonymous account helped trainee teachers mask concerns about personal writing skills and fear of criticism from others, indicating that anonymity may alter communication patterns, particularly in the early stages of network use. Given the data collected in this case study, and the interpretations placed on it by the author, a pessimistic assessment of the place of electronic networking in initial teacher education courses was presented. For this situation to change - that is, for electronic discussions to become more fully integrated into course activities - four issues which need to be addressed were identified and discussed. These included clarification of the role of collaboration amongst participants in initial teacher education, the ways in which collaboration can be facilitated using electronic networking, the problems of notation - such as the difficulty of expressing ideas about teaching in written form, and the concerns about permanently archived messages - for teachers and trainee teachers, and the lack of skills which many trainee teachers bring to electronic discussions. In the context of initial teacher education, it was suggested that these four aspects require clarification and development before the potential advantages of electronic networking can be realised. Some specific suggestions about how these issues might be resolved were presented.

Obtenção das freqüências naturais em torres estaiadas pelo método da matriz de transferência, representando o feixe de cabos por uma rigidez horizontal dinâmica

O objetivo do presente trabalho é o estudo do comportamento, em termos de freqüências naturais de estruturas de torres estaiadas, para diversas situações de serviço. Para isso criou-se uma formulação para a determinação dessas freqüências, utilizando o método da matriz de transferência. O procedimento consiste na discretização da estrutura em elementos de barras, massas discretas, molas e amortecedores viscosos, para a representação da estrutura. Com relação aos cabos da torre estaiada, desenvolveu-se uma expressão que nos fornece a rigidez completa dos mesmos, apoiados nos extremos, com amortecimento viscoso e as propriedades físicas e geométricas uniformes. Além disso, os cabos podem ser inclinados e sujeitos à excitação horizontal harmônica no apoio superior. Nesse caso, considera-se uma deformada parabólica do cabo na posição de equilíbrio estático, e por outro lado, os deslocamentos dinâmicos são considerados pequenos. A rigidez do cabo é válida para um ângulo de inclinação que varia de zero (0) a noventa (90) graus. Esse método é aplicável a microcomputadores devido a pouca memória empregada no processamento de dados. Com esse intuito, foi elaborado um programa para microcomputadores de 16 bits, que possibilita o estudo da estrutura da torre sobre o efeito de flexão pura, torção pura ou acoplamento de ambos. Exemplos numéricos de torres estaiadas e do comportamento da rigidez de cabos foram desenvolvidos para as mais diversas situações de cálculo.

Análise dos requisitos e planos de produção gerados por um sistema de planejamento fino de produção

O tema central deste trabalho é o Planejamento, Programação e Controle da Produção na indústria, com o auxílio de uma ferramenta computacional, do tipo Finite Capacity Schedule (FCS). No Brasil, essa categoria de software é denominada, genericamente, por Sistemas de Planejamento Fino de Produção ou de Capacidade Finita. Alinhado com as tendências mundiais e a vantagem de menores investimentos em hardware, o sistema escolhido é compatível com a operação em microcomputadores. Na primeira parte do trabalho, o assunto é tratado de forma geral, quando se pretende caraterizar amplamente o problema da programação da produção, as dificuldades na sua execução, as soluções existentes e suas limitações. A segunda parte do trabalho discute, detalhadamente, os métodos tradicionais de planejamento de materiais e capacidade. A revisão bibliográfica se encerra com uma apresentação dos sistemas FCS e sua classificação. A terceira parte trata da descrição, ensaios e avaliação da programação gerada por um software de Planejamento Fino de Produção determinístico, baseado na lógica de simulação computacional com regras de decisão. Embora a avaliação esteja limitada ao software utilizado, a análise ainda vai procurar identificar as diferenças fundamentais entre os resultados da programação de Capacidade Finita e a convencional, representada pelos sistemas da categoria MRPII ou Planejamento dos Recursos de Manufatura (Manufacturing Resources Planning). As lógicas dos sistemas MRPII e de Capacidade Finita são discutidas na revisão bibliográfica, enquanto que, para o software empregado no trabalho, ainda há um capítulo específico tratando da sua descrição, fundamentos, software house, hardware necessário e outras informações relevantes. Os ensaios serão implementados com o objetivo de analisar o sistema FCS como ferramenta de planejamento e de programação de produção. No caso, uma fração de um processo produtivo será modelada no sistema, através do qual serão gerados planos de produção que serão confrontados com a programação usual e com o comportamento real dos recursos envolvidos. Os ensaios serão realizados numa das unidades pertencentes a uma empresa transnacional de grande porte, que atua no ramo de pneumáticos. Por último, são apresentadas as conclusões gerais, recomendações na aplicação do sistema estudado e sugestões para futuras pesquisas relacionadas com o assunto.

Uso do computador em educação: um estudo do Projeto Ciranda

O surgimento do computador provocou uma série de mudanças sócio-culturais. A educação não poderia ficar imune a essas alterações. Várias experiências do seu uso em educação surgiram, inicialmente em computadores de grande porte; posteriormente, com o surgimento dos microcomputadores, essas experiências se multiplicaram. Como esse equipamento vem sendo utilizado, avaliações já realizadas, alguns problemas existentes e perspectivas futuras são discutidas neste trabalho; que procura apresentar o Projeto Ciranda, implantado pela Embratel. Tendo como pano de fundo uma perspectiva educacional, discute a filosofia do projeto, seus objetivos e a população participante.

Administração da implementação dos recursos de informática

A tese identifica as dimensões essenciais da administração da implementação dos recursos de Informática, cria estruturas de referência que capturam estas dimensões e analisa este processo multidimensional e contingencial utilizando como exemplo de TI-Tecnologia de Informação a microinformática. Neste sentido, desenvolve e quantifica uma série de índices para o planejamento e controle da implementação do método proposto, através da análise de casos reais e de uma pesquisa.

Modelo iterativo para estimativa da evapotranspiração de referência provável

O presente trabalho teve por objetivo a apresentação de um modelo iterativo para utilização em microcomputadores capaz de estimar valores de evapotranspiracão de referencia em diversos níveis de probabilidade, a partir de uma série de dados. O procedimento matemático envolvido na técnica iterativa empregada relaciona-se à utilização das funções de densidade gama incompleta e beta. Para tanto, foram utilizados dados quinzenais de evapotranspiracão do mês de março, a partir de uma série de 30 anos para a região de Piracicaba-SP. Através do teste de Kolmogorov-Smirnov, verificou-se que dados estimados através do modelo apresentaram alto grau de ajuste com dados relatados em literatura, justificando assim sua utilização.

Representacao grafica de dados multidimensionais com o auxilio de microcomputador

Software in BASIC (GWBASIC, version 2.0) and TURBO PASCAL (version 3.0) is presented for PC type microcomputers with the purpose of calculating the graphical method for multivariate data according to Andrews. Applying both softwares to data from the Irati Formation mesossaurides skull measures, in velocity and graphical quality, the TURBO PASCAL language performed better. -after English summary

Towards an intelligent graphical interface for linear programming modelling

The increase of computing power of the microcomputers has stimulated the building of direct manipulation interfaces that allow graphical representation of Linear Programming (LP) models. This work discusses the components of such a graphical interface as the basis for a system to assist users in the process of formulating LP problems. In essence, this work proposes a methodology which considers the modelling task as divided into three stages which are specification of the Data Model, the Conceptual Model and the LP Model. The necessity for using Artificial Intelligence techniques in the problem conceptualisation and to help the model formulation task is illustrated.