7,746 research outputs found
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Coordinating a Robot Arm and: Multi-finger Hand Using the Quaternion Representation
An autonomous hand-arm system must be able to move its multiple fingertips to specified 3-D world locations. We present an algorithm which, given a desired position and normal for each fingertip, computes all the joint angles for the fingers and arm. Our primary method for handling this under-constrained problem is to optimize a cost function. We also give methods for generating good candidates to be optimized. We present several new techniques for using the quaternion form to optimize rotation. We give experimental results from using the algorithm to apply complicated grasps with a Utah/MIT hand-arm system
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Robot Active Touch Exploration: Constraints and Strategies
We investigate the problem of using active touch ("haptic") exploration to recognize a 3D object taken from a known set of models. "That is new is that we combine two approaches: (1) using geometric constraints between components to eliminate interpretations, and interpretation tree methods for choosing the best active sensing move; (2) exploratory moves made by tracing continually along the surface of the object (and not through free space). We restrict ourselves to polyhedral, and give a set of geometric constraints tailored for matching components acquired from haptic exploration against components in the models. We present a new constraint using pairs of line segments. We then give a set of active sensing moves, each with an associated cost measure, and our strategies for choosing the next move
The politics of inequality and redistribution in Latin America's post-adjustment era
Declining social and economic inequalities since the late 1990s coincided with several basic shifts in Latin America's political landscape, including an electoral turn to the left and a revival of social mobilization from below. These shifts helped to 'repoliticize' inequality and return redistributive policies to a central place on the political agenda in the aftermath to the structural adjustment policies of the 1980s and 1990s.Equity gains, however, have occurred under conservative governments as well as leftist ones, and they are associated with a diverse set of public policy initiatives. The new politics of inequality, therefore, differ significantly from those of Latin America's ISI era, as well as those that prevailed during the period of economic liberalization
ICAN sensitivity analysis
A computer program called Integrated Composite Analyzer (ICAN) was used to predict the properties of high-temperature polymer matrix composites. ICAN is a collection of NASA Lewis Research Center-developed computer codes designed to carry out analysis of multilayered fiber composites. The material properties used as input to the program were those of the thermoset polyimide resin PMR-15 and the carbon fiber Celion 6000. The sensitivity of the predicted composite properties to variations in the resin and fiber properties was examined. In addition, the predicted results were compared with experimental data. In most cases, the effect of changes in resin and fiber properties on composite properties was reasonable. However, the variations in the composite strengths with the moisture content of the PMR-15 resin were inconsistent. The ICAN-predicted composite moduli agreed fairly well with experimental values, but the predicted composite strengths were generally lower than experimental values
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Learning the Probability Distribution for Probabilistic Expert Systems
This paper describes a method for learning the joint probability distribution of a set of variables from a sample of instances from the domain. The method is based on a straightforward application of Bayes Law to the problem of estimating individual probabilities from a probability distribution. We use a maximum entropy distribution as an initial estimate and show how this estimate can be easily updated each time an additional example is observed. Although developed for the purpose of estimating the conditional probabilities required for Bayesian inference networks, this method can be adopted to simplify knowledge acquisition in any expert system that uses knowledge in the form of probabilities
Exchange-Rate Economics for the Resources Sector
The paper provides an account of aspects of exchange-rate economics that are of particular relevance to the resources sector. The issues discussed include exchange-rate volatility and risk management practices used to deal with it, the role of productivity differences across countries, the impact of a booming resources sector on the country’s exchange rate and approaches to forecasting exchange rates. The discussion is organised around a simple stylised model that emphasises the quantity theory of money and purchasing power parity as a long-run link between prices and exchange rates.
Higher Education Exchange: 2007
This annual publication serves as a forum for new ideas and dialogue between scholars and the larger public. Essays explore ways that students, administrators, and faculty can initiate and sustain an ongoing conversation about the public life they share.The Higher Education Exchange is founded on a thought articulated by Thomas Jefferson in 1820: "I know no safe depository of the ultimate powers of the society but the people themselves; and if we think them not enlightened enough to exercise their control with a wholesome discretion, the remedy is not to take it from them, but to inform their discretion by education."In the tradition of Jefferson, the Higher Education Exchange agrees that a central goal of higher education is to help make democracy possible by preparing citizens for public life. The Higher Education Exchange is part of a movement to strengthen higher education's democratic mission and foster a more democratic culture throughout American society.Working in this tradition, the Higher Education Exchange publishes interviews, case studies, analyses, news, and ideas about efforts within higher education to develop more democratic societies
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An Integrated System for Dextrous Manipulation
This paper describes an integrated system for dextrous manipulation using a Utah-MIT hand that allows one to look at the higher levels of control in a number of grasping and manipulation tasks. The system consists of a number of low-level system primitives for grasping, integrated hand and robotic arm movement, tactile sensors mounted on the fingertips, sensing primitives to utilize joint position, tendon force and tactile array feedback, and a high-level programming environment that allows task level scripts to be created for grasping and manipulation tasks. A number of grasping and manipulation tasks are described that have been implemented with this system
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