A distributed model of robot task synchronization and interaction
Vassilios George Kountouris · 1992
In this dissertation, we develop a distributed model of robot task synchronization and interaction by utilizing developments from universal algebra, the theory of algebraic specifications, and Petri net theory. The novelty of this model is that it allows for the dynamic specification of the distributed semantics of multiagent systems, in general, and robot systems, in particular. This is in contrast to the traditional practice of the static specification of the interleaving semantics of such systems. More specifically, the distributed model that is developed in this dissertation provides the means to perform the following: (1) The specification of a plan for the execution of a task. (2) The hierarchical decomposition of a plan. (3) The distribution and localization of the resulting plan components to the appropriate agents. (4) The determination and specification of the temporal order on the control flow of tasks of multiple agents. (5) The synchronization of concurrent tasks when necessary. (6) The determination and specification of the interactions of concurrent tasks. Thus, the distributed model that is developed in this dissertation is a significant step towards the realization of robot systems that exhibit a high degree of autonomy. The realization of such systems is desirable because (i) they will greatly enhance the task-executing versatility of contemporary robot systems, and (ii) they will allow for robotic applications in unstructured environments such as space and underwater exploration, contaminated areas, and agriculture. The distributed model that we develop in this dissertation has been utilized for the development of a task-executor that translates a robot-independent plan into robot actions. Qualitative results from two case studies illustrate the plausibility of the developed model. The model also allows for the incorporation of quantitative measures for performance evaluation. However, in the absence of a benchmark for comparison, from any prior work that we are aware of, quantitative results have not been obtained. The distributed model that is developed in this dissertation is also applicable to domains other than the intelligent robot control. Intuitively, it seems most appropriate in dynamic domains which are characterized by an inherent hierarchical structure.