Embodied Evolution Richard A. Watson, Sevan G. Ficici {richardw, sevan}@cs.brandeis.edu

One of our robots.

Robot underside showing the four contact points that collect power from the floor.

The robot pen for the phototaxis experiments: showing eight Tupperbots, the power-floor and the light in the center.

The figure below shows the frequency with which the light is successfully reached by the robot population ('hit rate') over time. All experiments used a population of eight Tupperbots. The embodied evolution experiment evolves the weights from an initial condition where all weights are zero. We also tested a hand-designed solution which (after considerable 'tuning') achieves approximately 10 hits per minute. Embodied evolution produces a population with a performance that exceeds the hand-designed solution after about one hour. Interestingly, the evolved solutions exhibit qualitatively different behavior from our hand-designed solution: we designed a Braitenberg-style [1984] 'swagger,' but evolution favoured a spiraling solution.

Mean hit rate over time for embodied evolution and two control experiments; hand-designed weights, and random weights. EE and designed data is averaged over six runs, random averaged over two runs. The dotted lines are +/- one standard deviation. A time window of 20 minutes is used to compute the instantaneous hit rate for each data point on the graph.