Modeling Hydra Behavior Using Methods Founded in Behavior-Based Robotics

Modeling Hydra Behavior Using Methods Founded in Behavior-Based RoboticsMaster’s Thesis in Engineering MechatronicsMALIN AKTIUSDepartment of Applied MechanicsDivision of Vehicle SafetyChalmers University of TechnologyAbstractIn this thesis work methods from the field of behavior-based robotics are used to modelthe behavior of a biological organism. The cnidarian Hydra was selected as the modelorganism for this project, and the colony-style architecture was chosen as the method tobe used for organizing the constituent behaviors of Hydra into an overall behavior. Theindividual behaviors were generated and organized in a simulated animal. Validation ofthe individual behaviors were carried out with respect to quantitative data available frompreviously conducted experiments on the animal. In the case of the overall behavior,which emerged from the organization of the individual behaviors using the colony-stylearchitecture, only a qualitative comparison was feasible. Tests conducted on the modeledHydra suggests that the colony-style architecture can be used to model behavior propertieslike latency, activation threshold, habituation, and duration of the individual behaviors ofHydra. Simulations of the overall behavior of the animal show that the spatial movementpatterns of Hydra in the absence of external stimuli, as well as the effect of starvation onits contraction frequency, agrees with results from experiments conducted on the physicalanimal.Keywords: behavior-based modeling, Hydra, colony-style architecture, evolutionary algorithms,recurrent neural networks.i