Master-Slave Disc Assembler are commonly used in transportation scenarios where daughter trays circulate with goods outside the warehouse. Typically, the quality of daughter trays circulating outside the warehouse is poor, which is detrimental to the stable operation of automated transportation systems. Before entering the warehouse, the stacking machine combines the daughter trays with the mother trays before storage. Using the mother-daughter tray combination satisfies the requirements for stable operation of the automated transportation system and also saves product circulation costs.