The analysis and optimization of repetition within robot workcell sequencing problems

The authors introduce a classification of sequencing problems according to the presence of nondeterminism, whether due to the structure of the problem itself (internal) or to online events (external). They develop a theory, in the context of timed Petri nets, of how repetition can be described and predicted. They conclude with a description of a PROLOG-based decision-support system which manages this nondeterminism by exploring the consequences of alternate orderings of workcell operations, and ultimately constructs the time-optimal sequence. The analysis and optimization are illustrated with an example