A Fine-Grained Alternative to the Subsumption Architecture for Mobile Robot Control

Abstract

We present an architecture for robot control which can be viewed as a very fine-grained layered architecture motivated by the principles underlying the subsumption architecture. The subsumption architecture provides a powerful means for defining intelligent robot control mechanisms through the layered composition of simple behaviors. However, we have found that there are basic limitations inherent in this architecture due to the inaccessibility of information internal to a behavior. While adhering to the basic concept of building a robot control system through successive layers of competence, task achieving behaviors in our system are fragmented into many smaller decision-making units. Each of these units simply has the task of transforming a set of input activations into an output activation, so that the role that any unit plays in the system is defined entirely by how it is connected to other units. This fine-grained nature of our architecture permits a more flexible arbitration of commands between behaviors and provides incrementally added behaviors with complete access to the internal state of existing behaviors. A detailed example of an operational robot control system for cross-country navigation is given.