  The idea of symbolic controllers tries to bridge the gap between the top-down
manual design of the controller architecture, as advocated in Brooks'
subsumption architecture, and the bottom-up designer-free approach that is now
standard within the Evolutionary Robotics community. The designer provides a
set of elementary behavior, and evolution is given the goal of assembling them
to solve complex tasks. Two experiments are presented, demonstrating the
efficiency and showing the recursiveness of this approach. In particular, the
sensitivity with respect to the proposed elementary behaviors, and the
robustness w.r.t. generalization of the resulting controllers are studied in
detail.
