A three-level net formalism for the modeling of multiple mobile robot systems

This paper explores qualitative modelling of multiple mobile robot systems. The approach held is Petri net (PN)-based: a definition of a three-level net system in which the tokens may be PNs, called 3LNS, is presented. The formalism allows the definition of net modules at three levels; the interaction among modules is described through transition synchronization. Furthermore a modelling methodology using 3LNS is proposed; the upper level describes the robots, environment, the next level models the general behaviour of the mobile robots, and the third level represents specific features of each robot namely mission, tasks, and roadmaps; at this level resources and robot interaction protocols are also described. The use of 3LNS is illustrated through a case study regarding a mobile robot community evolving into a structured environment.