The main focus of the current study was to quantify the chemical signals received by a blue crab (Callinectes sapidus) tracking a source in a laboratory flume. To make a direct linkage between tracking behavior and the odorant concentration signal, we developed a measurement system to quantify the instantaneous concentration field surrounding actively tracking blue crabs. A three-dimensional laser-induced fluorescence (3DLIF) system was designed and constructed to measure odorant concentrations around crabs tracking three source types: a continuous release with exit velocity matching the mean local velocity in the flume; a continuous release with a meander created by an upstream cylinder; and a pulsed release switching on and off and with the same mass flow rate as the other two plume types. The meandering and pulsed plumes were introduced to observe the effects of large-scale spatial (meandering) and temporal (pulsed) intermittency on crab tracking. Simultaneous with the chemical concentration measurements, crab position data was recorded for kinematic analysis during post-processing. In addition, concentration measurements were collected for the three plume types without crabs present in order to quantify the statistical characteristics of the plume structure The concentration signals arriving at the antennules and outer chemosensory organs, most notably the legs, were targeted due to the hypotheses that concentration bursts at the antennules mediate upstream movement and that spatial contrast at the leg chemosensors mediates turning. A sampling zone was placed in front of the crab's mouth parts and aligned with the crab carapace orientation to extract odorant bursts at the antennules. The data generally showed an increase in upstream walking speed when high concentration bursts arrive at the antennules location, which agrees with the hypothesis. Measurement of the odorant concentration at the outer chemosensors was less direct and involved placing a box upstream of the crab and sampled earlier in time in order to avoid shadowing interference. Based on the signal at the upstream sampling box, a general bias for turning was observed. Crabs casted transversely in response to the directional bias extracted from the upstream sampling box. A statistical analysis of crab behavioral response to concentrations at the antennules and outer chemosensors can be found in a (future) companion thesis written by Jennifer Page in the School of Biology. Data were also taken for the three plume types in the absence of blue crabs. The continuous plume average statistics displayed Gaussian behavior at nozzle centerline. The meandering plume data conformed to the meandering plume model of Gifford (1959), modified for an induced pseudo-periodic meander. The pulsed plume displayed characteristics intermediate between the cloud dispersion model (Townsend 1951, Chatwin and Sullivan 1979) and the Gaussian dispersion model for a continuous release. For the three plume types, the standard deviation of the concentration fluctuations was greater than the average concentrations, as time records consisted of intermittent high concentrations interspersed with concentrations close to zero.

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Magistrinio darbo tikslas – įgyvendinti, graužikų biologinio, aplinkos žymėjimo kvapais ir navigacijos, proceso modelį robotikos srityje. Graužikai aplinkoje orientuojasi analizuodami informaciją gautą iš skirtingų penkių jutimo organų. Regėjimas padeda suvokti aplinkos erdvę, reljefą, atstumus iki objektų. Klausa, suteikia informaciją apie aplink esančius garso šaltinius, besiartinančius gyvūnus. Lytėjimas, padeda nustatyti objekto paviršiaus savybes: karštas ar šaltas, drėgnas ar sausas, minkštas ar kietas. Uoslė ir skonio receptoriai naudojami nustatyti maisto šaltiniui ar teritorijos riboms. Realiame biologiniame pasaulyje gyvūnai gali lengvai analizuoti informaciją gautą iš skirtingų jutimo organų ir ją derinti erdvinės navigacijos procese. Dirbtinėje sistemoje šie duomenys yra gaunami iš sensorių pasižyminčių skirtingomis savybėmis ir techniniais parametrais. Projekto tikslas - išspręsti robotikos uždavinį: tikslo paieškos navigacija naudojant aplinkos žymėjimą. Sukurta sistema imituoja graužiko erdvinės navigacijos procesą naudojant du skirtingus jutimo sensorius: dirbtinę regą ir dirbtinę uoslę. Projekte pristatoma sukurta sistema ir realizuoti erdvinės navigacijos algoritmai naudojantys vaizdinę ir kvapo informaciją. Aprašoma eksperimento vykdymo metodika ir priemonės. / The aim of the master thesis is to implement, rodent’s biological, goal directed navigation based on self-marking process in robotics. Rodents in environment navigate using analyzed information that gets from five different senses. Seeing helps to realize environment’s space, relief, distance from the objects. Hearing sense gives information about sound position of sound sources or other animals. Touch sense helps to determine properties of the surface: is it cold or hot, dry or wet, soft or hard. Olfactory and flavor receptors are used to determine food source or territory range. In real biological world animals could easily analyze and combine information from different sense receptors in spatial navigation process. In artificial system this data we are getting from different type and characteristics sensors. The main aim of this project is to solve robotic task: goal directed navigation based on self -marking method. Created system simulates rodent’s spatial navigation process where in two sensors are used: artificial eyes and artificial nose. This project presents created system and implemented spatial navigation algorithms which are using video and odor tracking based information. The methodology and tools used in experiment are described in this paper.

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