Analysis of Decentral Order-picking Control Concepts

Abstract

A paradigm change in the control logic of material flows is propagated towards self-controlled objects that take decisions decentrally as a reaction to cope with the increasing complexity. However, the technical feasibility has yet to be proven, esp. with regard to in-house material handling. For a successful implementation in future planning rules, the overall system performance as well as adapted system hardware is to be investigated. The paper focuses onto part-to-picker order-picking systems (OPS) with the use of AS/RS, which are typically operated by a central control system. The challenge for decentral control concepts is the formulation of optimal control strategies without information of the current system status. By means of a reference model and simulations runs KPIs and various operating strategies are compared between the two different control philosophies. The analyses yield that decentral control strategies are suitable for the operation of part-to-picker OPS, where they control bin supply to a series of order picking stations that even operate according to the inverse picking principle, i.e. parallel picking at the order picking stations. By means of adapted operating strategies a comparable system performance, measured in picks/hr or picker utilization, can be achieved.