Anytime Learning and Adaptation of Structured Fuzzy Behaviors

Abstract

We present an approach to support effective learning and adaptation of behaviors for autonomous agents with reinforcement learning algorithms. These methods can identify control systems that optimize a reinforcement program, which is, usually, a straightforward representation of the designer's goals. Reinforcement learning algorithms usually are too slow to be applied in real time on embodied agents, although they provide a suitable way to represent the desired behavior. We have tackled three aspects of this problem: the speed of the algorithm, the learning procedure, and the control system architecture. The learning algorithm we have developed includes features to speed up learning, such as niche-based learning, and a representation of the control modules in terms of fuzzy rules that reduces the search space and improves robustness to noisy data. Our learning procedure exploits methodologies such as learning from easy missions and transfer of policy from simpler environments to the more complex. The architecture of our control system is layered and modular, so that each module has a low complexity and can be learned in a short time. The composition of the actions proposed by the modules is either learned or predefined. Finally, we adopt an anytime learning approach to improve the quality of the control system on-line and to adapt it to dynamic environments. The experiments we present in this article concern learning to reach another moving agent in a real, dynamic environment that includes nontrivial situations such as that in which the moving target is faster than the agent and that in which the target is hidden by obstacles.