Evolutionary optimisation of neural network models for fish collective behaviours in mixed groups of robots and zebrafish

Animal and robot social interactions are interesting both for ethological studies and robotics. On the one hand, the robots can be tools and models to analyse animal collective behaviours, on the other hand, the robots and their artificial intelligence are directly confronted and compared to the natural animal collective intelligence. The first step is to design robots and their behavioural controllers that are capable of socially interact with animals. Designing such behavioural bio-mimetic controllers remains an important challenge as they have to reproduce the animal behaviours and have to be calibrated on experimental data. Most animal collective behavioural models are designed by modellers based on experimental data. This process is long and costly because it is difficult to identify the relevant behavioural features that are then used as a priori knowledge in model building. Here, we want to model the fish individual and collective behaviours in order to develop robot controllers. We explore the use of optimised black-box models based on artificial neural networks (ANN) to model fish behaviours. While the ANN may not be biomimetic but rather bio-inspired, they can be used to link perception to motor responses. These models are designed to be implementable as robot controllers to form mixed-groups of fish and robots, using few a priori knowledge of the fish behaviours. We present a methodology with multilayer perceptron or echo state networks that are optimised through evolutionary algorithms to model accurately the fish individual and collective behaviours in a bounded rectangular arena. We assess the biomimetism of the generated models and compare them to the fish experimental behaviours.Comment: 10 pages, 4 figure

How to Blend a Robot within a Group of Zebrafish: Achieving Social Acceptance through Real-time Calibration of a Multi-level Behavioural Model

We have previously shown how to socially integrate a fish robot into a group of zebrafish thanks to biomimetic behavioural models. The models have to be calibrated on experimental data to present correct behavioural features. This calibration is essential to enhance the social integration of the robot into the group. When calibrated, the behavioural model of fish behaviour is implemented to drive a robot with closed-loop control of social interactions into a group of zebrafish. This approach can be useful to form mixed-groups, and study animal individual and collective behaviour by using biomimetic autonomous robots capable of responding to the animals in long-standing experiments. Here, we show a methodology for continuous real-time calibration and refinement of multi-level behavioural model. The real-time calibration, by an evolutionary algorithm, is based on simulation of the model to correspond to the observed fish behaviour in real-time. The calibrated model is updated on the robot and tested during the experiments. This method allows to cope with changes of dynamics in fish behaviour. Moreover, each fish presents individual behavioural differences. Thus, each trial is done with naive fish groups that display behavioural variability. This real-time calibration methodology can optimise the robot behaviours during the experiments. Our implementation of this methodology runs on three different computers that perform individual tracking, data-analysis, multi-objective evolutionary algorithms, simulation of the fish robot and adaptation of the robot behavioural models, all in real-time.Comment: 9 pages, 3 figure

Co-ordination of cell cycle and differentiation in the developing nervous system

During embryonic development, cells must divide to produce appropriate numbers, but later must exit the cell cycle to allow differentiation. How these processes of proliferation and differentiation are co-ordinated during embryonic development has been poorly understood until recently. However, a number of studies have now given an insight into how the cell cycle machinery, including cyclins, CDKs (cyclin-dependent kinases), CDK inhibitors and other cell cycle regulators directly influence mechanisms that control cell fate and differentiation. Conversely, examples are emerging of transcriptional regulators that are better known for their role in driving the differentiated phenotype, which also play complementary roles in controlling cell cycle progression. The present review will summarise our current understanding of the mechanisms co-ordinating the cell cycle and differentiation in the developing nervous system, where these links have been, perhaps, most extensively studied

Chilling of carcasses from double muscled cattle: time-temperature evolution and predictive modelling of growth of Listeria monocytogenes and Clostridium perfringens

The time/temperature combination during carcass chilling is of concern in order to avoid bacterial growth. The chilling speed is lower in carcasses with high muscular development such as large cattle from the Belgian Blue breed. Three slaughterhouses were selected for temperature and pH measurements during the chilling process at 6 different days on 4 half carcasses in order to obtain representative data from heavy carcasses with high muscular development. Predictive microbiology was used to evaluate the potential growth of Listeria monocytogenes and Clostridium perfringens on the surface and in the depth of the carcasses. The gamma concept was chosen as secondary model taking into account the effect of temperature, pH and water activity on the selected bacteria during the chilling process. The predicted growth potential of Listeria monocytogenes is influenced by the different environmental conditions of the selected slaughterhouses and could reach 1.4 log CFU/cm² after the chilling process. The potential growth of Clostridium perfringens is limited due to unfavourable conditions during the first hours and to low temperature later. It can be concluded that when the initial level of contaminating bacteria is not excessive the speed at which the carcass is currently chilled is sufficient to limit the growth of these two pathogens and to ensure the product quality

Animal-robot interactions: at the crossroad of biology and robotics

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Recrutement de groupe et rôle des leaders chez la fourmi Tetramorium caespitum: approche expérimentale et théorique

L’exploitation collective de ressources par les sociétés animales repose sur la coopération et la coordination des membres du groupe. Selon la structure sociale des espèces envisagées, leurs comportements collectifs seront dictés par quelques individus imposant leurs choix ou au contraire impliqueront tous les membres du groupe. Chez la fourmi Tetramorium caespitum, la récolte de nourriture repose à la fois sur le dépôt d’une piste de phéromone chimique commune lors du retour des ouvrières vers le nid et sur le recrutement de groupe de congénères guidés par des individus leaders jusqu’à la source de nourriture. Cette espèce nous donne donc l’opportunité d’étudier un système de recrutement couplant des mécanismes décentralisés à la présence d’individus leaders.Nos observations montrent que le recrutement de groupe est lié à une forte motivation de certaines ouvrières à exploiter une source de nourriture découverte. Lorsqu’elles recrutent un groupe, elles passent peu de temps à l’intérieur du nid mais effectuent un taux élevé de contacts avec leurs congénères, principalement à l’entrée du nid, avant de repartir en direction de la nourriture, suivie par le peloton de fourrageuses. Durant le trajet, si une trajectoire rectiligne et une faible vitesse de déplacement favorisent la probabilité des recrutées d’atteindre la source, la perte de recrutées n’entraîne cependant aucune modification du comportement de la meneuse. Enfin, un suivi individualisé des fourrageuses au cours du recrutement montre que la probabilité d’être observée en tant que leader est répartie de manière homogène entre les individus découvrant la source de nourriture, sans influence du nombre de trajets qu’elles ont déjà effectués.Par ailleurs, nous avons étudié l’influence des leaders sur les choix collectifs de la colonie. Les leaders modulent les caractéristiques du recrutement -­-fréquence des groupes, tailles des groupes-­- en fonction des caractéristiques de la source exploitée. Grâce à un modèle multi-­-agents, nous avons démontré que cette modulation du recrutement permet à la colonie entière de focaliser son effort d’affourragement sur la nourriture la plus avantageuse lorsque plusieurs sources sont disponibles dans l’environnement. Enfin, nous avons développé un modèle mathématique décrivant le couplage du recrutement de groupe et du dépôt d’une piste chimique. Grâce à l’étude des états stationnaires de ce modèle, nous avons démontré que la présence des leaders est un élément indispensable à l’initiation de l’exploitation collective d’une ressource chez T. caespitum. Ainsi, les leaders de groupe permettent d’atteindre plus aisément un nombre seuil d’ouvrières à la source qui soit suffisant pour permettre l’émergence d’une piste chimique commune assurant à elle seule un recrutement de masse. Les résultats de cette thèse placent dans une nouvelle perspective notre vision des phénomènes de leadership chez les insectes sociaux. A l’échelle individuelle, ils mettent en évidence le statut temporaire de ces leaders chez Tetramorium caespitum basé sur leur propre motivation et les conditions locales du recrutement ;à l’échelle collective, ils soulignent le rôle complémentaire et facilitateur des leaders qui vont permettre l’émergence de structures auto-­- organisées impliquant l’ensemble de la fourmilière.Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

Accuracy of leadership and control of the audience in the pavement ant Tetramorium caespitum

In the ant species Tetramorium caespitum, collective foraging relies on group mass communication in which successful scouts lay a recruitment trail but also guide a group of nestmates to the food source. We conducted experiments to understand how group leaders may improve the success of recruits in reaching the food source and whether they adjust their leading behaviour to their audience, that is, to the following response of recruits along the foraging journey. We characterized the trajectories of leaders by measuring their straightness, angular deviation, maximal amplitude and walking speed. Trajectometric values highlighted that a straight path coupled with a slow walking speed increased the probability of followers reaching the food whereas leaders that walked at higher speed and deviated far from the food-nest beeline were more likely to lose recruits. Leaders did not seem to heed their audience since they did not reduce their speed or their path sinuosity after the loss of a recruit along their outbound journey. Information transfer about food resources by T.caespitum leaders is thus targeted towards a restricted number of recruits but without the informed individuals exerting any control over the following response of their audience. We discuss strengths and weaknesses of group recruitment compared with simpler or more sophisticated forms of information sharing and we debate the status of group recruiters regarding the concept of leadership in animal groups. © 2014 The Association for the Study of Animal Behaviour.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Tuning of group recruitment in the ant Tetramorium caespitum

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La fourmilière :un swarm de bio-senseurs

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