Hybrid Order Picking Systems: a Literature Review and a Simulation-Based Study

One of the most significant activities undertaken in a warehouse is Order Picking, which can be defined as "the process of retrieving products from storage (or buffer areas) in response to a specific customer request." Several studies have demonstrated that Order Picking is the most labour-intensive and costly task in warehouses. Consequently, it is imperative to recognize the strategic importance of Order Picking Process in warehouse management. In recent years, mainly due to the growth of e-commerce, the importance of this process has increased, particularly given the need to fulfill orders more quickly. For this reason, automation has become essential for gaining a competitive advantage. This thesis will present the historical evolution of Order Picking and analyze the state of the art of Hybrid Order Picking Systems, i.e., systems in which picking operators and robots cooperate, sharing the same workspace, in order to fulfill orders. Following an analysis of the extant literature, it is evident that this type of system has received limited attention in literature. Consequently, Tecnomatix Plant Simulation software will be utilized to perform a discrete-event simulation of a warehouse divided zones (Zoning) with different types of orders. In each zone, the picking process will be performed by either a human picker or a robot picker. The analysis to be conducted following the simulation will present a comparison in terms of time and cost of different case scenarios. This will highlight the economic advantage of using human pickers for larger orders and robots for smaller orders.