Compensation of position errors in passivity based teleoperation over packet switched communication networks

Because of the use of scattering based communication channels, passivity based telemanipulation systems can be subject to a steady state position error between master and slave robots. In this paper, we consider the case in which the passive master and slave sides communicate through a packet switched communication channel (e.g. Internet) and we provide a modification of the slave impedance controller for compensating the steady state position error arising in free motion because of packets loss

UNIFIED MODELING OF CONTROL SOFTWARE AND PHYSICAL PLANTS

n/

Port-contact systems in bilateral telemanipulation

In this paper we develop one of the first control applications of the recently proposed port-contact framework. We show how it is possible to model and control a bilateral telemanipulation system using port-contact systems and we develop a port-contact impedance controller that allows to impose a desired interactive behavior and a zero steady state position error during contact tasks

Single and Double Photoionization and Photodissociation of Toluene by Soft X-rays in Circumstellar Environment

The formation of polycyclic aromatic hydrocarbons (PAHs) and their methyl derivatives occurs mainly in the dust shells of asymptotic giant branch (AGB) stars. The bands at 3.3 and 3.4 $\mu$m, observed in infrared emission spectra of several objects, are attributed C-H vibrational modes in aromatic and aliphatic structures, respectively. In general, the feature at 3.3 $\mu$m is more intense than the 3.4 $\mu$m. Photoionization and photodissociation processes of toluene, the precursor of methylated PAHs, were studied using synchrotron radiation at soft X-ray energies around the carbon K edge with time-of-flight mass spectrometry. Partial ion yields of a large number of ionic fragments were extracted from single and 2D-spectra, where electron-ion coincidences have revealed the doubly charged parent-molecule and several doubly charged fragments containing seven carbon atoms with considerable abundance. \textit{Ab initio} calculations based on density functional theory were performed to elucidate the chemical structure of these stable dicationic species. The survival of the dications subjected to hard inner shell ionization suggests that they could be observed in the interstellar medium, especially in regions where PAHs are detected. The ionization and destruction of toluene induced by X-rays were examined in the T Dra conditions, a carbon-rich AGB star. In this context, a minimum photodissociation radius and the half-life of toluene subjected to the incidence of the soft X-ray flux emitted from a companion white dwarf star were determined.Comment: 11 pages, 4 figures, accept for publication in Ap

Edge-Weighted Consensus Based Formation Control Strategy With Collision Avoidance

In this paper, a consensus-based control strategy is presented to gather formation for a group of differential-wheeled robots. The for- mation shape and the avoidance of collisions between robots are ob- tained by exploiting the properties of weighted graphs. Since mobile robots are supposed to move in unknown environments, the presented approach to multi-robot coordination has been extended in order to include obstacle avoidance. The effectiveness of the proposed control strategy has been demonstrated by means of analytical proofs. More- over, results of simulations and experiments on real robots are provided for validation purposes

Parameter identification for piecewise-affine fuzzy models in noisy environment

AbstractIn this paper the problem of identifying a fuzzy model from noisy data is addressed. The piecewise-affine fuzzy model structure is used as non-linear prototype for a multi–input, single–output unknown system. The consequents of the fuzzy model are identified from noisy data which are collected from experiments on the real system. The identification procedure is formulated within the Frisch scheme, well established for linear systems, which is extended so that it applies to piecewise-affine, constrained models

Recuento de Staphylococcus aureus y de coliformes, con previa recuperación de celulas injuriadas

p.291-295En el presente trabajo se analizaron 20 muestras de leche en polvo con el objeto de determinar el porcentaje de células injuriadas de Staphylococcus aureus y de coliformes durante los procesos de elaboración de dicho producto (calor y desecación). Estas muestras fueron seleccionadas de un total de 80 por haber sido detectada en ellas presencia de Staphylococcus aureus. Se siguió una metodología de aceptación general (Speck, 1976) y las determinaciones fueron efectuadas con y sin recuperación previa de células injuriadas. Se encontró que el porcentaje de células injuriadas osciló entre el 18,5 y el 77,7 por ciento en el caso de Staphylococcus aureus y entre el 25 y el 62,5 por ciento, en el caso de los coliformes. Cuando no se observó aumento en el recuento, con previa recuperación de células injuriadas, debe asumirse que la contaminación es posterior a la elaboración. En el caso de las bacterias coliformes, esta contaminación posterior parece más factible y los numerosos recuentos negativos se explican por el muy bajo porcentaje de supervivencia a los procesos de elaboración de la leche en polvo: 0,002 por ciento (Chopin, Mocquot y Le Graet, 1977)

Measurement and classification of human characteristics and capabilities during interaction tasks

In this paperwe address the need to design adaptive interacting systems for advanced industrial production machines. Modern production systems have become highly complex and include many subsidiary functionalities, thus making it difficult for least skilled human operators interact with them. In this regard, adapting the behavior of the machine and of the operator interface to the characteristics of the user allows a more effective interaction process, with a positive impact on manufacturing efficiency and user's satisfaction. To this end, it is crucial to understandwhich are the user's capabilities that influence the interaction and, hence, should be measured to provide the correct amount of adaptation.Moving along these lines, in this paper we identify groups of users that, despite having different individual capabilities and features, have common needs and response to the interaction with complex production systems. As a consequence,we define clusters of users that have the same need for adaptation. Then, adaptation rules can be defined by considering such users' clusters, rather than addressing specific individual user's needs

The shell middens of the Bay of Daun: environmental changes and human impact along the coast of Las bela (Balochistan, Pakistan) between the 8th and the 5th millennium BP

The discovery of shell middens around the bay of Daun and Lake Siranda (Las Bela, Balochistan) shows that groups of prehistoric gatherers settled alon the coast of Las Bela at least sincethe last two centuries of the 8th millennium BP. The radiocarbon dating of the Daun sites indicates that the exploitation of the mangrove resources was not continuous, but took place mainly during distinct periods of the 7th and 5th millennia BP. The radiocarbon dates from marine and mangrove shells from the Tharro anf Makli Hills (Lower Sindh) suggest that the coastal seafaring along the northern coast of the Arabian Sea began already around the beginingof the 7th millennium B