An On-line Constructive Heuristic to Optimise the Hybrid Pick and Place Machine

Abstract

This work focuses on optimising the hybrid pick and place machine which is a new surface mount device placement machine. We present an on-line constructive heuristic to schedule the component pick and place operations. The machine begins a pickup and placement operation once the first placement point is scheduled. While the machine is moving, picking or placing other components, the scheduler concurrently schedules the subsequent placement points. Since a nozzle change operation is very expensive (it significantly adds to the overall assembly time), the constructive heuristic gives highest priority to minimising the number of nozzle changes, then maximising simultaneous vision operations, simultaneous pickup and same tour pickup operations. Finally, when all the available placement points, which have components available on the feeder slots, have been scheduled by the constructive heuristic, we then reoptimise the schedule by minimising the nozzles changes. Computational results are presented