Bi-objective Assignment Model for Lean Order Picking in a Warehouse

With the introduction of Lean Warehousing, we are committed to using lean principles for more efficient warehousing operations, which are performed with quality and safety. Manual order picking, on which the paper is focused, is currently considered the most unfriendly to humans because, in the long run, it contributes to the appearance of musculoskeletal disorders. We record not only the increase in the average age of employees in warehouses but also in the number and duration of sick leave due to back and muscle pain. This paper explores the possibility of productive work while preventing order pickers from Work-Related Musculoskeletal Disorders. Using a laboratory experiment, we determine retrieval times for units with different characteristics and study required postures by guidelines of Revised NIOSH Lifting Equation. The final goal is to create a bi-objective assignment model.