Localisation d'objets pour les non-voyants : augmentation sensorielle et neuroprothèse

Les difficultés éprouvées par les non-voyants au quotidien peuvent être classées dans quatre domaines principaux : l'accès à l'information écrite, le déplacement, l'orientation et la reconnaissance/localisation d'objets. C'est sur la conception d'un système de suppléance permettant aux non-voyants de reconnaître et de localiser des objets que porte cette thèse. L'état de l'art des systèmes de suppléance visuelle fait apparaître deux catégories de systèmes: les systèmes de substitution et d'augmentation sensorielle. Les premiers capturent une image basse résolution de la scène visuelle en la transformant pour être restituée dans autre modalité sensorielle (tactile ou auditive). Ces systèmes expérimentaux ne sont aujourd'hui pas utilisables du fait de la difficulté d'interprétation du signal restitué. Les seconds augmentent un canal sensoriel (tactile ou auditif) en restituant une faible quantité d'information identifiée comme pertinente pour améliorer l'autonomie des personnes non-voyantes. C'est cette dernière approche qui a été développée dans cette thèse en restituant une fonction du système visuel : la localisation d'objets. La restitution de cette information de position sur un objet a été envisagée selon deux modes de restitution : " auditive " dans un système d'augmentation sensorielle et " visuelle " pour la simulation d'une neuroprothèse corticale. Les perspectives de ces travaux permettent d'envisager un outil de suppléance pour l'aide à la navigation des non-voyants, en fusionnant un système de géolocalisation pour le positionnement, de vision artificielle pour reconnaître des objets dans la scène visuelle et de sonification pour restituer ces informations.The difficulties experienced by blind people in their daily lives can be classified in four main areas: read, write, orientation and recognition and localization of objects. This manuscript addresses this last topic of object recognition and localization. The state of the art of assistive devices for the Blind shows two types of aid: Sensory substitution and sensory augmentation systems. The first category captures a low resolution image of the visual scene which is converted to a signal that can be interpreted by another sensory modality (tactile or auditory). Those experimental systems are currently not usable because of the difficulty to interpret the restituted signal. Sensory augmentation systems are more usable. They increase a sensory channel (auditory or tactile) restituting a small amount of information identified as relevant to improve independence of blind people. This latter approach was developed in this thesis by restoring one lost visual function: localizing objects. A system was developed to restore this function of the human visual system. The restitution of the location of an object has been studied in two ways: in an auditory sensory augmentation system and a "visual" system for the simulation of a visual neuroprosthesis. The prospects for this work (some of which were included in the NAVIG project) are the first steps of the design of an assistive device which could help the Blind to navigate in unknown environments. This system relies on a GPS system for navigation, vision to recognize objects in the visual scene and a sonification system to restitute this information

ARTIFICIAL VISION FOR THE BLIND: A BIO-INSPIRED ALGORITHM FOR OBJECTS AND OBSTACLES DETECTION

International audienceAlthough artificial vision systems could potentially provide very useful input to assistive devices for blind people, such devices are rarely used outside of laboratory experiments. Many current systems attempt to reproduce the visual image via an alternative sensory modality (often auditory or somatosensory), but this dominant 'scoreboard' approach, is often difficult to interpret for the user. Here we propose to offload the recognition problem onto a separate image processing system that then provides the user with just the essential information about the location of objects in the surrounding environment. Specifically, we show that a bio-inspired image processing algorithm (SpikeNet) can robustly, precisely and rapidly recognize and locate key objects in the image, but also in space if the objects are in a stereoscopic field of view. In addition, the bio-inspired algorithm allows real time calculation of optic flow. We hence propose that this system, coupled with a restitution interface allowing localization in space (i.e. 3D virtual sounds synthesis) can be used to restore essential visuomotor behaviors such as grasping desired objects and navigating (finding directions, avoiding obstacles) in unknown environments

Interaction of soluble organic matter with metal oxides used as ceramic membrane for drinking water pretreatment

Throughout the world, a trend to intensify use of desalination as a means to reduce current or future water scarcity is observed. Membrane desalination is an extremely good technique for the removal of colloids, dissolved organic matter and salts. However this technique is very sensitive to fouling. Therefore, it is important to control the fouling of the Reverse Osmosis membrane to insure a long lifetime of the membrane. Pretreatment is a good way to control the fouling. In this project, ceramic membrane ultrafiltration is considered as pretreatment before RO. Interactions between organic matter from different sources and ceramic membranes are studied to evaluate the efficiency of ceramic ultrafiltration as a pretreatment before RO. Terrestrial organic matter extracted from a treatment plant and marine organic matter from algae culture and sea are investigated. These organic materials show different organic content, hydrophobic character and molecular weight distribution (LC-OCD profiles). Filtration of marine organic matter leads to higher fouling than terrestrial organic matter (decline of 85% in the first ten minutes for Chlorella vulgaris exudates), for a smaller content of organic matter (DOC of marine solutions = 3 - 4 mg/L; DOC of brackish water = 10 mg/L). Analyses of backflush and chemical cleaning solutions show that Low Molecular Weight (LMW) compounds and High Molecular Weight (HMW) compounds are preferentially retained in the ceramic membrane. © 2012 American Water Works Association

Reaching to Sound Accuracy in the Peri-personal Space of Blind and Sighted Humans

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Localisation d'objets pour les non-voyants (augmentation sensorielle et neuroprothèse)

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Route selection algorithm for blind pedestrian

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Ceramic membrane as a pretreatment for reverse osmosis: Interaction between marine organic matter and metal oxides

Scaling and (bio)fouling phenomena can severely alter the performance of the reverse osmosis process during desalination of seawater. Pretreatments must be applied to efficiently remove particles, colloids, and also precursors of the organic fouling and biofouling. Ceramic membranes offer a lot of advantages for micro and ultrafiltration pretreatments because their initial properties can be recovered using more severe cleaning procedure. The study focuses on the interaction between metal oxides and marine organic matter. Experiments were performed at laboratory scale. The first series of experiments focus on the filtration of different fractions of natural organic matter and model compounds solutions on flat disk ceramic membranes (47 mm of diameter) characterized with different pore size and composition. Direct filtration experiments were conducted at 0.7 bar or 2 bars and at room temperature (20 ± 0.5 °C). The efficiency of backflush and alkaline cleaning were eval, and titanium oxides. Each metal oxide corresponds to a specific pore size for the disk ceramic membranes: 80, 60, and 30 nm. Different sizes of metal oxide particles are used to measure the impact of the surface area on the adsorption of the organic matter. Seawaters from the Arabian Gulf and from the Red Sea were collected during algal blooms. Cultures of algae were also performed in the laboratory and in cooperation with woods hole oceanographic institute. Solutions of algal exudates were obtained after a couple of weeks of cultivation followed by sonication. Solutions were successively filtered through GFF (0.7 lm) and 0.45 lm membrane filters before use. The dissolved organic carbon (DOC) concentration of final solution was between 1 and 4 mg/L and showed strong hydrophilic character. These various solutions were prepared with the objective to mimic the dissolved organic matter composition of seawater subjected to algal bloom. Characterization of the solutions of filtration experiments (feed water, permeate water, and back-washes) and batch experiments (raw solution and supernatant solutions) included fluorescence, UV, total organic carbon, total nitrogen, and Liquid Chromatography - Organic Carbon Detection measurements. In comparison to seawater under normal condition, seawa- ters collected during algal bloom and algal exudates solutions led to very severe fouling of all ceramic membranes (with some DOC removal of 10-20%). It is important to indicate that algal exudate permeates still exert fouling properties when filtered through similar new (virgin) membrane. These results indicate that both size exclusion and adsorption phenomena occur (on surface, inside pores). In all cases, the backflush (performed with MilliQ [MQ]) showed minor or no effect and the cleaning backwash was not able to recover the initial flux (30-60%). Analyses performed on the backflush solution (performed with MQ) and on the alkaline cleaning solution revealed the retention of both high and low molecular organics on the different metal oxides. Unfortunately, analyses of membrane surface using imaging various tools are not providing informative results in term of foulant/adsorbed material composition. © 2013 Desalination Publications. All rights reserved

Designing an assistive device for the blind based on object localization and augmented auditory reality

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