Goods-to-person picking is a warehouse system in which inventory is brought to a fixed pick station instead of workers walking long distances through storage aisles. Mobile robots, conveyors, lifts, or shuttles move totes, bins, or racks to an operator who selects items for customer orders. This matters because walking can take more than half of the time in traditional order picking, so reducing travel can greatly improve speed, accuracy, and worker comfort.
The central idea is to keep people or robotic arms focused on the value-adding step: choosing the correct item and placing it into the correct order container.
A typical system begins when warehouse software receives orders and decides which inventory containers are needed at each station. Autonomous mobile robots or other automated devices retrieve storage units, queue them in the right sequence, and present them at an ergonomic workstation with lights, screens, scanners, and bins. The system must balance robot traffic, station workload, inventory availability, and order deadlines so that neither workers nor robots wait too long.
Good design uses data such as pick rate, travel time, queue size, and order mix to increase throughput while reducing errors and congestion.
Key Facts
- Throughput = completed picks per hour.
- Pick rate = total items picked / total picking time.
- Order cycle time = order completion time - order release time.
- Robot utilization = active robot time / total available robot time.
- Station utilization = busy station time / total available station time.
- Little's Law for a stable system: WIP = throughput x flow time.
Vocabulary
- Goods-to-person picking
- A fulfillment method where automated equipment brings inventory to a fixed worker or robot station for picking.
- Autonomous mobile robot
- A self-navigating warehouse robot that moves racks, totes, or carts without following a fixed track.
- Pick station
- A workstation where inventory is presented and items are transferred into order bins or cartons.
- Throughput
- The rate at which a warehouse system completes picks, orders, or units over time.
- Queue
- A line of waiting robots, totes, orders, or tasks that are ready for the next processing step.
Common Mistakes to Avoid
- Counting robot movement as picking time, which is wrong because picking time refers to the human or robotic action of selecting items, while robot travel is a separate handling activity.
- Assuming more robots always increase throughput, which is wrong because stations, aisles, elevators, chargers, or software limits can become bottlenecks.
- Ignoring queue time at the pick station, which is wrong because waiting totes or robots can raise order cycle time even when individual picks are fast.
- Designing only for average demand, which is wrong because warehouses must handle peaks, rush orders, product shortages, and uneven order mixes.
Practice Questions
- 1 A pick station completes 420 item picks in 2 hours. What is the station throughput in picks per hour?
- 2 A robot is active for 42 minutes during a 60 minute period. What is its utilization as a percentage?
- 3 A warehouse adds robots but order completion time does not improve. Explain two possible bottlenecks in a goods-to-person system that could prevent throughput from increasing.