An improved ant colony algorithm for dynamic hybrid flow shop scheduling with uncertain processing time

In this article the scheduling problem of dynamic hybrid flow shop with uncertain processing time is investigated and an ant colony algorithm based rescheduling approach is proposed. in order to reduce the rescheduling frequency the concept of due date deviation is introduced, according to which a rolling horizon driven strategy is specially designed. considering the importance of computational efficiency in the dynamic environment, the traditional ant colony optimization is improved. on the one hand, a strategy of available routes compression to restrict ants’ movement is proposed so that the ants’ searching cycle for new solutions could be shorten. on the other hand, illuminating function in state transfer possibility is improved to facilitate the exploration of low pheromone trail. performance of rolling horizon procedure and rescheduling algorithm are evaluated respectively through simulations, the results show the best parameters of rolling horizon procedure and demonstrate the feasibility and efficiency of rescheduling algorithm. an example from the practical production is addressed to verify the effectiveness of the proposed approach.