Order dividing optimisation in crane & shuttle-based storage and retrieval system

The crane & shuttle-based storage and retrieval system (C&SBS/RS) is the first automated warehouse technology that supports pallet picking, case picking and item picking. In the C&SBS/RS, aisle-captive cranes perform pallet picking, while tier-captive shuttles handle cases and items picking. To balance picking tasks, we propose an order dividing algorithm to fulfil required specific picking sequences. The optimisation objective is to minimise the order line picking time. Therefore, we modelled and analyzed the C&SBS/RS and considered single and dual command cycles for each resource (i.e. cranes, rail-guided vehicles, shuttles and lifters) separately according to their respective operation processes. Finally, numerical experiments were conducted to analyze impact factors and a real case to verify the power of the proposed order dividing algorithm.