54 research outputs found

    Airborne chemical sensing with mobile robots

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    Airborne chemical sensing with mobile robots has been an active research areasince the beginning of the 1990s. This article presents a review of research work in this field,including gas distribution mapping, trail guidance, and the different subtasks of gas sourcelocalisation. Due to the difficulty of modelling gas distribution in a real world environmentwith currently available simulation techniques, we focus largely on experimental work and donot consider publications that are purely based on simulations

    Multivariable Fuzzy Control Based Mobile Robot Odor Source Localization via Semitensor Product

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    In order to take full advantage of the multisensor information, a MIMO fuzzy control system based on semitensor product (STP) is set up for mobile robot odor source localization (OSL). Multisensor information, such as vision, olfaction, laser, wind speed, and direction, is the input of the fuzzy control system and the relative searching strategies, such as random searching (RS), nearest distance-based vision searching (NDVS), and odor source declaration (OSD), are the outputs. Fuzzy control rules with algebraic equations are given according to the multisensor information via STP. Any output can be updated in the proposed fuzzy control system and has no influence on the other searching strategies. The proposed MIMO fuzzy control scheme based on STP can reach the theoretical system of the mobile robot OSL. Experimental results show the efficiency of the proposed method

    Optimal Spatial Formation of Swarm Robotic Gas Sensors in Odor Plume Finding

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    Finding the best spatial formation of stationary gas sensors in detection of odor clues is the first step of searching for olfactory targets in a given space using a swarm of robots. Considering no movement for a network of gas sensors, this paper formulates the problem of odor plume detection and analytically finds the optimal spatial configuration of the sensors for plume detection, given a set of assumptions. This solution was analyzed and verified by simulations and finally experimentally validated in a reduced scale realistic environment using a set of Roomba-based mobile robots

    Le sens du goût chez l'aveugle congénital

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    ThĂšse rĂ©alisĂ©e en collaboration avec le DĂ©partement de neurosciences et pharmacologie de l'UniversitĂ© de Copenhague, Danemark.La vision est cruciale dans la recherche et l’identification de nourriture. Non seulement elle dĂ©clenche le rĂ©flexe cĂ©phalique de la digestion mais, combinĂ©e Ă  l’expĂ©rience alimentaire, elle aide Ă  raffiner nos prĂ©visions par rapport aux aliments. En un simple clin d’Ɠil, la vue renseigne sur la disponibilitĂ©, l’identitĂ©, la comestibilitĂ©, les saveurs, les textures et les contenus nutritionnel, calorique et toxique des aliments qui nous entourent. Étant donnĂ©e l’importance de la vue dans l’expĂ©rience gustative, il est judicieux de se poser la question suivante : Qu’arrive-t-il au goĂ»t en absence de vision? Cette thĂšse rĂ©pond Ă  cette question par l’étude de cette modalitĂ© chez l’aveugle de naissance grĂące aux techniques de psychophysique et d’imagerie cĂ©rĂ©brale. De plus, les consĂ©quences gustatives de la cĂ©citĂ© sont comparĂ©es Ă  celles suivant la perte d’un autre sens important dans l’apprĂ©ciation des aliments, soit l’odorat (anosmie). Les rĂ©sultats comportementaux dĂ©montrent premiĂšrement que l’absence de vision depuis la naissance abaisse la sensibilitĂ© gustative, reflĂ©tĂ©e par des seuils Ă©levĂ©s de dĂ©tection et d’identification des cinq goĂ»ts de base (sucrĂ©, salĂ©, acide, amer, umami). DeuxiĂšmement, bien que les aveugles congĂ©nitaux aient plus de facilitĂ© Ă  identifier les odeurs comestibles par leurs narines (voie olfactive orthonasale), ceux-ci perdent leur avantage par rapport aux voyants quand ils doivent identifier ces stimuli placĂ©s sur la langue (voie olfactive rĂ©tronasale). Les rĂ©sultats d’imagerie indiquent en outre que les aveugles congĂ©nitaux activent moins leur cortex gustatif primaire (insula/opercule) et leur hypothalamus par rapport aux voyants durant une tĂąche gustative. De plus, l’absence d’activation dans le cortex (« visuel ») occipital chez l’aveugle pointe vers le manque de plasticitĂ© intermodale en gustation. Chez les anosmiques congĂ©nitaux d’autre part, non seulement l’absence d’odorat diminue l’habiletĂ© Ă  reconnaĂźtre les goĂ»ts mais elle abaisse Ă©galement la force du signal dans les aires olfactives (ex : cortex orbitofrontal mĂ©dial) durant une tĂąche gustative. Les rĂ©sultats chez l’aveugle contrastent grandement avec les Ă©tudes antĂ©rieures soulignant l’amĂ©lioration de leurs sens extĂ©roceptifs tels que l’audition, l’olfaction (orthonasale) et le toucher qui font tous intervenir la plasticitĂ© intermodale. Par ailleurs, les donnĂ©es chez l’anosmique concordent avec ceux de la littĂ©rature indiquant une diminution similaire de la chĂ©mosensation trigĂ©minale, laquelle est Ă©galement associĂ©e Ă  un affaiblissement du circuit neural des saveurs. Ceci suggĂšre que le sens du goĂ»t ne soit pas utile aux handicapĂ©s visuels pour percevoir l’environnement extĂ©rieur et ainsi compenser leur perte de vision. De plus, bien que l’odorat participe Ă  l’apprĂ©ciation de la nourriture en bouche, sa perte n’entraĂźne pas de compensation sensorielle chez l’anosmique. Prises ensemble, ces donnĂ©es indiquent diffĂ©rents mĂ©canismes d’adaptation suivant la cĂ©citĂ© et l’anosmie. Elles soutiennent Ă©galement le point de vue selon lequel la perception unifiĂ©e de goĂ»ts et de saveurs inclut non seulement les sens chimiques et le toucher mais Ă©galement la vision. ConsidĂ©rant l’importance du goĂ»t et de l’alimentation dans la qualitĂ© de vie, ces rĂ©sultats encouragent la sociĂ©tĂ© tout comme les professionnels de la rĂ©adaptation Ă  faciliter l’accĂšs Ă  la nourriture ainsi qu’à l’enseignement culinaire chez les handicapĂ©s sensoriels.Vision is crucial for seeking and identifying food. Not only does it trigger the cephalic digestion reflex but, when combined with the experience of eating, it helps to refine expectations about foods. In a single eye blink, sight informs us about the availability, identity, palatability, flavours, textures as well as nutritional, caloric and toxic contents of foods surrounding us. Given the importance of sight in the gustatory experience, one may therefore ask the following question: What happens to gustation without vision? This thesis answers this question by studying this modality in congenitally blind subjects using psychophysical and brain imaging techniques. Additionally, the gustatory consequences of blindness are compared to those following the loss of another important modality involved in the appreciation of food, i.e. the sense of smell (anosmia). Behavioural results first show that the absence of vision from birth reduces the gustatory sensitivity, as reflected by higher detection and identification thresholds of the five basic tastes (sweet, salty, acid, bitter, umami). Second, although congenitally blind subjects are better at identifying palatable odorant stimuli through their nostrils (orthonasal olfactory route), they lose this advantage over sighted people when identifying these stimuli placed on their tongue (retronasal olfactory route). Neuroimaging results also reveal that congenitally blind subjects activate the primary gustatory cortex (insula/operculum) and the hypothalamus less compared to blindfolded sighted participants. Moreover, the absence of occipital (“visual”) cortex activity in the blind points towards the lack of crossmodal plasticity in gustation. In congenitally anosmics, on the other hand, not only does the absence of smell lower the ability to recognize tastes but it also lowers the strength of the signal in olfactory areas (e.g. medial orbitofrontal cortex) during a gustatory task. The results in the blind greatly contrast with previous studies highlighting the enhancement of their exteroceptive senses such as audition, (orthonasal) olfaction and touch, all of which involve crossmodal plasticity. Moreover, data in the anosmic group are consistent with previous literature describing similar decrease of trigeminal chemosensation that is also associated with a weakening of the flavour neural network. This suggests that the sense of taste is not useful to the visually impaired to perceive their exterior environment and compensate for their lack of vision. Furthermore, although olfaction contributes to the appreciation of foods in the mouth, the lack of this modality does not drive sensory compensation in anosmic subjects. Taken together, these data indicate different adaptation mechanisms following blindness and anosmia. They also support the view according to which the unified perception of tastes and flavours includes not only the chemical senses (taste, smell and trigeminal chemosensation) and touch but also vision. Given the importance of taste and eating experience in quality of life, these results encourage society as well as rehabilitation professionals to facilitate access to foods and culinary lessons in sensory deprived subjects

    Proceedings of Abstracts, School of Physics, Engineering and Computer Science Research Conference 2022

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    © 2022 The Author(s). This is an open-access work distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. For further details please see https://creativecommons.org/licenses/by/4.0/. Plenary by Prof. Timothy Foat, ‘Indoor dispersion at Dstl and its recent application to COVID-19 transmission’ is © Crown copyright (2022), Dstl. This material is licensed under the terms of the Open Government Licence except where otherwise stated. To view this licence, visit http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3 or write to the Information Policy Team, The National Archives, Kew, London TW9 4DU, or email: [email protected] present proceedings record the abstracts submitted and accepted for presentation at SPECS 2022, the second edition of the School of Physics, Engineering and Computer Science Research Conference that took place online, the 12th April 2022

    Insect neuroethology of reinforcement learning

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    Historically, reinforcement learning is a branch of machine learning founded on observations of how animals learn. This involved collaboration between the fields of biology and artificial intelligence that was beneficial to both fields, creating smarter artificial agents and improving the understanding of how biological systems function. The evolution of reinforcement learning during the past few years was rapid but substantially diverged from providing insights into how biological systems work, opening a gap between reinforcement learning and biology. In an attempt to close this gap, this thesis studied the insect neuroethology of reinforcement learning, that is, the neural circuits that underlie reinforcement-learning-related behaviours in insects. The goal was to extract a biologically plausible plasticity function from insect-neuronal data, use this to explain biological findings and compare it to more standard reinforcement learning models. Consequently, a novel dopaminergic plasticity rule was developed to approximate the function of dopamine as the plasticity mechanism between neurons in the insect brain. This allowed a range of observed learning phenomena to happen in parallel, like memory depression, potentiation, recovery, and saturation. In addition, by using anatomical data of connections between neurons in the mushroom body neuropils of the insect brain, the neural incentive circuit of dopaminergic and output neurons was also explored. This, together with the dopaminergic plasticity rule, allowed for dynamic collaboration amongst parallel memory functions, such as acquisition, transfer, and forgetting. When tested on olfactory conditioning paradigms, the model reproduced the observed changes in the activity of the identified neurons in fruit flies. It also replicated the observed behaviour of the animals and it allowed for flexible behavioural control. Inspired by the visual navigation system of desert ants, the model was further challenged in the visual place recognition task. Although a relatively simple encoding of the olfactory information was sufficient to explain odour learning, a more sophisticated encoding of the visual input was required to increase the separability among the visual inputs and enable visual place recognition. Signal whitening and sparse combinatorial encoding were sufficient to boost the performance of the system in this task. The incentive circuit enabled the encoding of increasing familiarity along a known route, which dropped proportionally to the distance of the animal from that route. Finally, the proposed model was challenged in delayed reinforcement tasks, suggesting that it might take the role of an adaptive critic in the context of reinforcement learning

    A unified neural model explaining optimal multi-guidance coordination in insect navigation

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    The robust navigation of insects arises from the coordinated action of concurrently functioning and interacting guidance systems. Computational models of specific brain regions can account for isolated behaviours such as path integration or route following, but the neural mechanisms by which their outputs are coordinated remains unknown. In this work, a functional modelling approach was taken to identify and model the elemental guidance subsystems required by homing insects. Then we produced realistic adaptive behaviours by integrating different guidance's outputs in a biologically constrained unified model mapped onto identified neural circuits. Homing paths are quantitatively and qualitatively compared with real ant data in a series of simulation studies replicating key infield experiments. Our analysis reveals that insects require independent visual homing and route following capabilities which we show can be realised by encoding panoramic skylines in the frequency domain, using image processing circuits in the optic lobe and learning pathways through the Mushroom Bodies (MB) and Anterior Optic Tubercle (AOTU) to Bulb (BU) respectively before converging in the Central Complex (CX) steering circuit. Further, we demonstrate that a ring attractor network inspired by firing patterns recorded in the CX can optimally integrate the outputs of path integration and visual homing systems guiding simulated ants back to their familiar route, and a simple non-linear weighting function driven by the output of the MB provides a context-dependent switch allowing route following strategies to dominate and the learned route retraced back to the nest when familiar terrain is encountered. The resultant unified model of insect navigation reproduces behavioural data from a series of cue conflict experiments in realistic animal environments and offers testable hypotheses of where and how insects process visual cues, utilise the different information that they provide and coordinate their outputs to achieve the adaptive behaviours observed in the wild. These results forward the case for a distributed architecture of the insect navigational toolkit. This unified model then be further validated by modelling the olfactory navigation of flies and ants. With simple adaptions of the sensory inputs, this model reproduces the main characteristics of the observed behavioural data, further demonstrating the useful role played by sensory-processing to CX to motor pathway in generating context-dependent coordination behaviours. In addition, this model help to complete the unified model of insect navigation by adding the olfactory cues that is one of the most crucial cues for insects
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