A hierarchical model for coordinated planning and control of automated assembly manufacturing

A general, hierarchical model for describing automated assembly systems is developed. This hierarchical model allows any complex assembly system to be decomposed into simpler sub-systems. This decomposition can be applied recursively to generate a multi-level system structure. Planning and control can be performed on each part of this structure and, if necessary, between parts. The model was applied to a simulated dual-robot, surface-mount assembly system to simplify the problem of planning coordinated motions between the robots. For the purpose of illustration, both linear and polynomial motion-planning models were analyzed. Part pick-up and placement delays were also introduced. Furthermore, system performance as a function of the number of placement-nozzles was also quantified. By weighing the benefits of additional placement-nozzles against their costs, the ideal number of placement-nozzles may be determined.