Swarm Robotic Plume Tracking for Intermittent and Time-Variant Odor Dispersion

This paper presents a method for odor plume tracking by a swarm of robots in realistic conditions. In real world environments, the chemical concentration within an odor plume is patchy, intermittent and time-variant. This study shows that swarm robots can cooperatively track the odor plume towards its source by establishing a cohesive spatial sensor network to deal with the turbulences and patchy nature of odor plumes. The robots move together and maintain a distance margin between themselves in order to keep the cohesion of the constructed sensor network while the odor concentration and air-flow speed are considered in the equations of navigation of the robots in the network to more efficiently track the plume. The method is evaluated in simulation against various number of robots, the emission rate of the odor source, the number of obstacles in the environment and the size of the testing environment. The emergent behavior of the swarm proves the functionality, robustness and scalability of the system in different conditions

Airborne chemical sensing with mobile robots

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

Cluster Space Gradient Contour Tracking for Mobile Multi-robot Systems

Multi-robot systems have the potential to exceed the performance of many existing robotic systems by taking advantage of the cluster’s redundancy, coverage and flexibility. These unique characteristics of multi-robot systems allow them to perform tasks such as distributed sensing, gradient climbing, and collaborative work more effectively than any single robot system. The purpose of this research was to augment the existing cluster space control technique in order to demonstrate effective gradient-based functionality, specifically, that of tracking gradient contours of specified concentration levels. To do this, we needed first to estimate the direction of the gradient and/or contour based on the real-time measurements made by sensors on the distributed robots, and second, to steer the cluster in the appropriate direction. Successful simulation, characterization, and experimental testing with the developed testbed have validated this approach. The controller enabled the cluster to sense and follow a contour-based trajectory in a parameter field using both a kayak cluster formation and also the land based Pioneer robots. The positive results of this research demonstrate the robustness of the cluster space control while using the contour following technique and suggest the possibility of further expansion with field applications

Representations of Reward and Movement in Drosophila Dopaminergic Neurons

The neuromodulator dopamine is known to influence both immediate and future behavior, motivating and invigorating an animal’s ongoing movement but also serving as a reinforcement signal to instruct learning. Yet it remains unclear whether this dual role of dopamine involves the same dopaminergic pathways. Although reward-responsive dopaminergic neurons display movement-related activity, debate continues as to what features of an individual’s experience these motor-correlates correspond and how they influence concurrent behavior. The mushroom body, a prominent neuropil in the brain of the fruit fly Drosophila melanogaster, is richly innervated by dopaminergic neurons that play an essential role in the formation of olfactory associations. While dopaminergic neurons respond to reward and punishment to drive associative learning, they have also been implicated in a number of adaptive behaviors and their activity correlates with the behavioral state of an animal and its coarse motor actions. Here, we take advantage of the concise circuit architecture of the Drosophila mushroom body to investigate the nature of motor-related signals in dopaminergic neurons that drive associative learning. In vivo functional imaging during naturalistic tethered locomotion reveals that the activity of different subsets of mushroom body dopaminergic neurons reflects distinct aspects of movement. To gain insight into what facets of an animal’s experience are represented by these movement-related signals, we employed a closed loop virtual reality paradigm to monitor neural activity as animals track an olfactory stimulus and are actively engaged in a goal-directed and sensory-motivated behavior. We discover that odor responses in dopaminergic neurons correlate with the extent to which an animal tracks upwind towards the fictive odor source. In different experimental contexts where distinct motor actions were required to track the odor, dopaminergic neurons become emergently linked to the behavioral metric most relevant for effective olfactory navigation. Subsets of dopaminergic neurons were correlated with the strength of upwind tracking regardless of the identity of the odor and remained so even after the satiety state of an animal was altered. We proceed to demonstrate that transient inhibition of dopaminergic neurons that are positively correlated with upwind tracking significantly diminishes the normal approach responses to an appetitive olfactory cue. Accordingly, activation of those same dopaminergic neurons enhances approach to an odor and even drives upwind tracking in clean air alone. Together, these results reveal that the same dopaminergic pathways that convey reinforcements to instruct learning also carry representations of an animal’s moment-by-moment movements and actively influence behavior. The complex activity patterns of mushroom body dopaminergic neurons therefore represent neither purely sensory nor motor variables but rather reflect the goal or motivation underlying an animal’s movements. Our data suggest a fundamental coupling between reinforcement signals and motivation-related locomotor representations within dopaminergic circuitry, drawing a striking parallel between the mushroom body dopaminergic neurons described here and the emerging understanding of mammalian dopaminergic pathways. The apparent conservation in dopaminergic neuromodulatory networks between mammals and insects suggests a shared logic for how neural circuits assign meaning to both sensory stimuli and motor actions to generate flexible and adaptive behavior

Sensory landscape impacts on odor-mediated predator-prey interactions at multiple spatial scales in salt marsh communities

This collection of research examines how changes in the sensory landscape, mediated by both odor and hydrodynamic properties, impact odor-mediated predator-prey interactions in salt marsh communities. I approached this research using an interdisciplinary framework that combined field and laboratory experimentation to address issues of scale and make connections between predator behavior and patterns of predation in the field. I explored a variety of interactions mediated by changes in the sensory landscape including; indirect effects of biotic structure on associated prey, predator responses to patches of prey with differing density and distribution, and dynamic interactions between predators and prey distributions. I found that biotic structure (oyster reefs [Crassostrea virginica]) has negative indirect effects on associated hard clam prey (Mercenaria mercenaria) through the addition of oyster reef odor cues that attract predators (blue crabs [Callinectes sapidus] and knobbed whelks [Busycon carica])and increase foraging success near the structural matrix. Variation in the structure of patch-scale prey odor plumes created by multiple prey results in predator-specific patterns of predation as a function of patch density and distribution which are mediated by differences in predator sensory ability. There is a potential negative feedback loop between blue crab predators and hard clam prey distributions; clam patches assume random within-patch distributions after exposure to blue crab predators, making the detection of patches by future blue crab predators more difficult. Sensory landscapes are also mediated by water flow, which transports prey odor plumes downstream to predators. Characterization of water flow in small-scale estuary systems indicates that values of turbulent flow parameters are highly context specific and depend on both tidal type (spring, neap, normal) and site. Wind and tidal range seem to be good predictors for wave components and turbulent components of fluctuating flow parameters, respectively, although the strength of their predictive ability is dependent on time scale. Modifications of the sensory landscape through changes in structurally-induced turbulence, mixing of individual plumes from multiple prey, and bulk velocity and turbulence characteristics need to be considered when formulating predictions as to the impact of predators on naturally occurring prey populations in the field.Ph.D.Committee Chair: Marc Weissburg; Committee Member: Donald Webster; Committee Member: Julia Kubanek; Committee Member: Lin Jiang; Committee Member: Mark Ha

Information System for Environmental Technologies

Geographical Information Systems (GIS) play an important role in environmental management solutions, and they are being used with increasing frequency in environmental studies. The use of GIS technology in environmental studies provides a better way to manage, analyze, display and share the information. In this thesis, I automated a process for constructing GIS maps of odor complaints and inspections that have been used to study odor complaints in the vicinity of three landfills in Jefferson Parish. I provided an application that integrates daily environmental observation and monitoring data into a GIS and publishes the resulting maps through the Internet. The user\u27s interaction with the web-based maps does not require any GIS expertise. A Webapplication was also implemented for managing the list of the constructed maps. The maps are deleted or updated through the manager application, a friendly interface application that does not require users to have any GIS technology knowledge

Odour-mediated host seeking and discrimination in mosquitoes : chemistry, neurobiology and behaviour

The majority of the world’s population is at risk of one or more mosquito-borne diseases that are transmitted by blood-feeding female mosquitoes, affecting both human health and economic development. Especially Anopheles gambiae, the principal malaria vector, and Aedes aegypti, the vector of dengue and yellow fever, are of primary concern due to their strong specialisation on human hosts, and the high number of casualties caused by the pathogens they transmit. Host seeking and discrimination are crucial for disease transmission, and are predominantly mediated by olfaction. Using a wind tunnel system and a custom analysis pipeline, this thesis confirms that the two mosquito species use volatile host cues, derived from breath and body, differentially, as carbon dioxide on its own drives host seeking in Ae. aegypti, but not in An. gambiae (paper I). To discriminate between host and nonhost species (paper V), Ae. aegypti encode human identity by the relative activation of two glomeruli within the antennal lobe, the primary olfactory centre, of which one is tuned to long-chain aldehydes enriched in human odour. A synthetic blend mimicking the glomerular activation elicited host seeking in Ae. aegypti (paper II). Next to preferring human over non-human hosts, Ae. aegypti also prefer some human individuals to others, which was demonstrated to be affected by the ABO blood type and pregnancy or menstrual cycle phase. Analysis of the volatiles associated with individual volunteers, identified 1-octen-3-ol to be significantly associated with very high attractiveness (paper III). The molecular regulation of host seeking acquisition during An. gambiae female adult maturation was independent of odorant receptor gene AgamOR39 expression (paper IV). The results presented in this thesis contribute to the understanding of mosquito host seeking and discrimination from multiple perspectives, which is a prerequisite to ultimately develop novel tools for mosquito monitoring and control

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

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

GUARDIANS final report

Emergencies in industrial warehouses are a major concern for firefghters. The large dimensions together with the development of dense smoke that drastically reduces visibility, represent major challenges. The Guardians robot swarm is designed to assist fire fighters in searching a large warehouse. In this report we discuss the technology developed for a swarm of robots searching and assisting fire fighters. We explain the swarming algorithms which provide the functionality by which the robots react to and follow humans while no communication is required. Next we discuss the wireless communication system, which is a so-called mobile ad-hoc network. The communication network provides also one of the means to locate the robots and humans. Thus the robot swarm is able to locate itself and provide guidance information to the humans. Together with the re ghters we explored how the robot swarm should feed information back to the human fire fighter. We have designed and experimented with interfaces for presenting swarm based information to human beings