Dual commands dispatching of a class-based unit-load automated storage and retrieval system using multi-pass simulation with generic algorithm

A simulation system with the approach of multi-pass and genetic algorithm (MPGA) is developed for dispatching dual commands by a stacker machine in a unit-load/class-based automated storage and retrieval system (AS/RS). Three single-rules, FCFS/STT, SDT/STT, and STTbk, are run individually by a single-pass simulation and served as the benchmarks to compare with the performances of three kinds of the MPGA approach. All experiments, singles and MPGA, start with the same initial system states and run with the same input data streams. Due to a larger solution space for the optimal search and an iterative searching method, the MPGA approach greatly improves the performances of our AS/RS model, compared with traditional approaches.