Goods-to-person robots are autonomous mobile robots that bring inventory shelves, totes, or pods directly to a worker at a picking station. This changes warehouse work from walking long aisles to receiving the right items in a steady flow. The system matters because travel time is often one of the largest limits on order picking speed.
By reducing walking, it can improve throughput, accuracy, and worker ergonomics.
Key Facts
- Throughput = orders completed / time
- Robot travel time can be estimated by t = d / v when speed is constant.
- Cycle time = travel time + lift time + queue time + picking time + return time
- Utilization = busy time / available time
- Little's Law for a stable system is L = lambda W, where L is average items in system, lambda is flow rate, and W is average time in system.
- Goods-to-person systems reduce human travel distance by moving inventory pods to fixed picking stations.
Vocabulary
- Goods-to-person robot
- A mobile robot that transports shelves, pods, or totes from storage locations to a worker or automated station.
- Picking station
- A fixed workstation where a person or machine removes items from storage pods to fill orders.
- Pod
- A movable storage unit that holds many bins or shelves of inventory and can be carried by a robot.
- Fleet management system
- Software that assigns tasks, plans routes, manages traffic, and coordinates many robots at once.
- Throughput
- The rate at which a warehouse system completes work, such as orders picked per hour.
Common Mistakes to Avoid
- Assuming robots always move at top speed, which is wrong because traffic, turns, acceleration, lifting, and safety zones reduce average speed.
- Ignoring queue time at picking stations, which is wrong because even fast robots lose efficiency if pods wait in line for a worker.
- Counting robot travel only one way, which is wrong because a full task often includes going to a pod, bringing it to a station, and returning it to storage.
- Treating more robots as always better, which is wrong because too many robots can create congestion and lower the productivity of the whole system.
Practice Questions
- 1 A robot travels 48 m from storage to a picking station at an average speed of 1.2 m/s. How many seconds does the trip take?
- 2 A picking station completes 180 order lines in 2 hours. What is its throughput in order lines per hour? If a robot system increases this by 25%, what is the new throughput?
- 3 A warehouse manager wants to add more robots, but the picking stations are already busy almost all the time. Explain why adding robots may not increase total order throughput.