Human Like Adaptation of Force and Impedance in Stable and Unstable Tasks

Abstract—This paper presents a novel human-like learning con-troller to interact with unknown environments. Strictly derived from the minimization of instability, motion error, and effort, the controller compensates for the disturbance in the environment in interaction tasks by adapting feedforward force and impedance. In contrast with conventional learning controllers, the new controller can deal with unstable situations that are typical of tool use and gradually acquire a desired stability margin. Simulations show that this controller is a good model of human motor adaptation. Robotic implementations further demonstrate its capabilities to optimally adapt interaction with dynamic environments and humans in joint torque controlled robots and variable impedance actuators, with-out requiring interaction force sensing. Index Terms—Feedforward force, human motor control, impedance, robotic control. I

Some photometer results obtained on the NASA 1969 Airborne Auroral Expedition

The spectral features measured by a photometer onboard the Convair 990 Galileo, during the Auroral Expedition are given in tables. The measurements given cover flights 3 to 15

Survey of Diseases in Wild Turkeys in Arkansas

Nineteen dead wild turkeys were necropsied and 573 live wild turkeys were physically examined for pathological agents in Arkansas between 1992 and 1997 to determine the proximate role disease may play in declining wild populations in Arkansas. Necropsy of the dead wild turkeys identified avian pox and histomoniasis as the most common diseases (16% and 11% of necropsies, respectively). Avian pox was recorded from three major physiographic regions in the state (Ozark Highlands, Ouachita Mountains, Gulf Coastal Plain). One hen died of non-accidental crop impaction, the fifth occurrence observed in the southeastern United States. Another hen died after developing severe, focal necrotic dermatitis caused by a Penicillium sp. fungus, the first occurrence observed in wild turkeys. All live wild turkeys appeared free of gross signs of disease. We found diseases in wild turkeys in Arkansas are not uncommon and are more diverse than previously reported. Continued monitoring of disease in wild turkeys is therefore encouraged

Réalisation d'un dispositif expérimental pour l'étude des réactions de captures radiatives induites sur le lithium

Le dispositif décrit consiste en un évaporateur de lithium et un « vobulateur de position de cible ». L'évaporateur nous permet de préparer in situ des cibles exemptes de contaminations. Le « vobulateur » fait décrire à la cible une courbe de Lissajous par rapport au faisceau afin d'éviter la surchauffe de la cible

Critical collapse of collisionless matter - a numerical investigation

In recent years the threshold of black hole formation in spherically symmetric gravitational collapse has been studied for a variety of matter models. In this paper the corresponding issue is investigated for a matter model significantly different from those considered so far in this context. We study the transition from dispersion to black hole formation in the collapse of collisionless matter when the initial data is scaled. This is done by means of a numerical code similar to those commonly used in plasma physics. The result is that for the initial data for which the solutions were computed, most of the matter falls into the black hole whenever a black hole is formed. This results in a discontinuity in the mass of the black hole at the onset of black hole formation.Comment: 22 pages, LaTeX, 7 figures (ps-files, automatically included using psfig

Biasing in the Galaxy Distribution

We investigate the variation of galaxy clustering with luminosity using the recently completed SSRS2 sample. Clustering measurements based on the two-point correlation function and the variance of counts in cells reveal the existence of a strong dependence of the clustering amplitude on luminosity for galaxies brighter than L*, while no significant variation is detected for fainter galaxies. We derive a relative bias versus magnitude relation which can be compared with theoretical predictions. Existing models of galaxy formation cannot adequately reproduce the simultaneous steep rise of biasing at high luminosities and the plateau at the low-luminosity end. Improved modeling of the halo-galaxy relation and larger samples including low luminosity galaxies are required to draw more definitive conclusions.Comment: 29 pages including 5 figures (tarred, gzipped & uuencoded LaTeX & postscript files; postscript version including figures also available at http://www.bo.astro.it/bap/BAPhome.html); ApJ, accepted for publicatio