The Fifth International Symposium on Artificial Life and Robotics AROB 5th'00 From Life to Robotics: Social Robots S. Reimann & A. Mansour Institute for Autonomous intelligent Systems & BMC Research Center German National Research Center for & The Institute of Physical and Information Technology {\bf GMD} & Chemical Research ({\bf RIKEN}) Birlinghoven, Germany. & Nagoya, 463-003, JAPAN Abstract The formation of groups is of essential importance in biology. Aggregation is based on a simple dynamical model for the motion of each individual. It is shown that a {\em swarm} is formed within a short time span and is stable under perturbations. Keywords: Grouping behavior, stochastic control.