A collision-free sequencing algorithm for PWB assembly

The main task of printed wiring board (PWB) assembly is to mount electronic components on a PWB. The generation of efficient insertion and placement sequences will lead to significant time saving in assembly and thus save production cost. When generating insertion sequences, the first consideration is to avoid potential collision problems. This research is aimed at finding the minimum assembly time for each assembly machine through the generation of machine-head sequences and component sequences. Mathematical programming may be used to solve the sequence problem; however, the solution is computationally explosive and is impractical to implement. The proposed collision-free and closest-distance heuristic approach is based on the various characteristics of printed wiring assembly, such as insertion heads and component feeding types. This approach reduces the complexity of the problem and detects potential collisions before the generation of machine-head sequences and component sequences. Not only can the algorithm generate machine head sequence and component sequences effectively, it also guarantees no conflict between these two levels.