Integrating Robotic Functions And Operator Supervision Using Petri Nets

Abstract

Petri nets are a well established mod- elling technique for analyzing parallel systems. When coupled with an event-driven operatine system, Petri nets can provide an effective means for integrating and controlling the functions of distributed robotic appli- cations. Recent work has shown that Petri net graphs can also serve as remarkably intuitive operator inter- faces. In this paper the advantages for using Petri net as high-level controllers to coordinate robotic functions will be outlined; the considerations for designing Petri net controllers will be discussed; and simple Petri net structures for implementing an interface for operator supervision will be presented. I. INTRODUCTION The Theory of Intelligent Machines, as proposed in (8), describes a hierarchical organization of the functions of an autonomous robot into three levels: an Execution Level containing the hardware and basic control functions, a Coordination Level integrating the capabilities of the in- telligent machine (IM) across hardware systems, and an Organization Level providing higher-level planning and reasoning capabilities. Figure 1 illustrates this hierarchi- cal organization. An analytic formulation of the theory using information-theoretic measures of uncertainty for each level of the intelligent machine has been developed in recent years 9)(10). A long-term research goal of the ration (CIRSSE) is to attempt, guided by these theories, implementations of autonomous robots. In the past year at CIRSSE a computer architecture was developed that implements the lower two levels of the in- telligent machine (4). The architecture supports an event- Center for Intel I igent Robotic Systems for Space Explc-