Repetitive sequencing: from workcell tasks to workcell cycles

Given a workcell program defined as a set of repetitive tasks to be concurrently performed, one can associate with each workcell element (robots, vision systems, etc.) a repetitive partial order of operations; together, they define a workcell cycle. An evaluation of such cycles in terms of cycle time, task throughput, and machine utilization is proposed. To automate the sequencing analysis, a Prolog-based decision-support system, SAGE (sequence analysis by generalized enumeration), is presented. Given the specification of the work-cell program in terms of the operations to be performed by each workcell element, SAGE constructs all feasible cycles for exploring the space for all possible time evolutions of workcell behavior. Three variations on the same multirobot assembly example are used to illustrate the approach