A heuristic method for two-hoist cyclic scheduling with overlapping

Computer-controlled hoists are widely used for conveying material in production. The scheduling problem for one and two hoists is different, the latter involves overlapping and cannot be solved directly by means of mathematical modelling. A heuristic method is proposed by modeling subproblems associated with sequencing and linear programming. For each sequence, the whole problem is built and solved. Best scheduling is obtained by searching in the sequence space. A numerical example is solved to validate the proposed method.