20,292 research outputs found
An Active Pattern Recognition Architecture for Mobile Robots
An active, attentionally-modulated recognition architecture is proposed for object recognition and scene analysis. The proposed architecture forms part of navigation and trajectory planning modules for mobile robots. Key characteristics of the system include movement planning and execution based on environmental factors and internal goal definitions. Real-time implementation of the system is based on space-variant representation of the visual field, as well as an optimal visual processing scheme utilizing separate and parallel channels for the extraction of boundaries and stimulus qualities. A spatial and temporal grouping module (VWM) allows for scene scanning, multi-object segmentation, and featural/object priming. VWM is used to modulate a tn~ectory formation module capable of redirecting the focus of spatial attention. Finally, an object recognition module based on adaptive resonance theory is interfaced through VWM to the visual processing module. The system is capable of using information from different modalities to disambiguate sensory input.Defense Advanced Research Projects Agency (90-0083); Office of Naval Research (N00014-92-J-1309); Consejo Nacional de Ciencia y Tecnología (63462
Navite: A Neural Network System For Sensory-Based Robot Navigation
A neural network system, NAVITE, for incremental trajectory generation and obstacle avoidance is presented. Unlike other approaches, the system is effective in unstructured environments. Multimodal inforrnation from visual and range data is used for obstacle detection and to eliminate uncertainty in the measurements. Optimal paths are computed without explicitly optimizing cost functions, therefore reducing computational expenses. Simulations of a planar mobile robot (including the dynamic characteristics of the plant) in obstacle-free and object avoidance trajectories are presented. The system can be extended to incorporate global map information into the local decision-making process.Defense Advanced Research Projects Agency (AFOSR 90-0083); Office of Naval Research (N00014-92-J-l309); Consejo Nacional de Ciencia y Tecnología (63l462
Mass dependence of vector meson photoproduction off protons and nuclei within the energy-dependent hot-spot model
We study the photoproduction of vector mesons off proton and off nuclear
targets. We work within the colour dipole model in an approach that includes
subnucleon degrees of freedom, so-called hot spots, whose positions in the
impact-parameter plane change event-by-event. The key feature of our model is
that the number of hot spots depends on the energy of the photon--target
interaction. Predictions are presented for exclusive and dissociative
production of , , and off protons, as
well as for coherent and incoherent photoproduction of off nuclear
targets, where Xe, Au, and Pb nuclei are considered. We find that the mass
dependence of dissociative production off protons as a function of the energy
of the interaction provides a further handle to search for saturation effects
at HERA, the LHC and future colliders. We also find that the coherent
photonuclear production of is sensitive to fluctuations in the
subnucleon degrees of freedom at RHIC and LHC energies.Comment: 19 pages, 4 figures. Typo in legend of figs. 1 and 2 correcte
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