Optimization algorithm under relaxed constraints for sequencing component pick and placement in PCB assembly

Many optimization algorithms proposed for PCB assembly problem had a common problem that they introduced strong constraints, which made optimization performance deteriorate in practice. Focusing on component pick and placement sequencing problem for multi-head placement machine in PCB assembly, this paper discuss some strong constraints involved in related optimization problem and propose an algorithm under relaxed constraints for problem solving. Certain strong constraints were relaxed for the algorithm to expand solution space, making it possible to find better solutions. Under such relaxation, an optimization algorithm based on scatter search (SS) method was constructed to solve the component sequencing problem, and steps of algorithm are detailed in the paper. Numerical experiments were made to conduct an evaluation for the proposed algorithm, along with a comparison with two heuristic algorithms proposed in other literatures. The results show that the proposed algorithm has better performance in optimization results and can shorten PCB assembly time of the placement machine effectively.