Order batching in a bucket brigade order picking system considering picker blocking

摘要

Bucket brigade order picking improves operational productivity by balancing workloads among pickers with a minimal level of managerial planning and oversight. However, due to variability and uncertainty of the pick locations within a particular order or batch, pickers can encounter blocking delays and thus lose productivity. This study formulates a model to quantify blocking delays and develops a control model to reduce blocking in bucket brigade order picking systems. The Indexed Batching Model for Bucket brigades (IBMB) has indexed batching constraints for generating batch alternatives, bucket brigade picker blocking constraints for quantifying blocking delay, and release-time updating constraints for progressively connecting the batching results with blocking quantification. The IBMB minimizes total retrieval time and improves picker utilization from 2 to 9 % across diverse and practical order picking situations while maintaining the static Work-In-Process. We note that modeling the separation of retrieved batches into orders still remains a challenge.