Robotic case picking is the use of automated machines to select cartons, totes, or cases from pallets, racks, or storage locations and move them to an outbound flow. It matters because case picking is one of the most labor intensive and time sensitive jobs in a warehouse. A well designed robotic picking cell can improve throughput, reduce injuries from repeated lifting, and increase order accuracy.
In modern logistics, these systems help warehouses handle high order volume, labor shortages, and shorter delivery windows.
Key Facts
- Throughput rate = cases picked / hour
- Cycle time per pick = travel time + vision time + grip time + transfer time + release time
- Robot utilization = active picking time / scheduled time
- Payload capacity must be greater than carton mass plus gripper mass: P_robot > m_carton + m_gripper
- Pick accuracy = correct picks / total picks x 100%
- Conveyor flow rate = spacing speed relationship, Q = v / s, where Q is items per second, v is conveyor speed, and s is item spacing
Vocabulary
- Case picking
- Case picking is the process of selecting full cartons or cases from inventory to build customer orders.
- End effector
- An end effector is the tool mounted on a robot arm, such as a suction gripper or clamp, that interacts with objects.
- Machine vision
- Machine vision is a camera and software system that detects object position, shape, labels, and orientation.
- Throughput
- Throughput is the rate at which a system completes useful work, often measured in cases per hour.
- Warehouse management system
- A warehouse management system is software that tracks inventory, storage locations, orders, and work instructions.
Common Mistakes to Avoid
- Ignoring the gripper weight when checking payload is wrong because the robot must lift both the carton and the end effector safely.
- Using average cycle time only is wrong because peak demand, delays, and exception handling can limit real warehouse performance.
- Assuming every carton is easy to grip is wrong because glossy surfaces, damaged boxes, weak tape, and irregular shapes can reduce suction or clamp reliability.
- Placing a robot cell without considering upstream and downstream flow is wrong because conveyors, pallets, and mobile robots can become bottlenecks even if the arm is fast.
Practice Questions
- 1 A robotic picker completes one pick every 9 seconds on average. How many cases per hour can it pick if it runs continuously?
- 2 A robot has a rated payload of 25 kg. Its gripper has a mass of 6 kg, and each carton has a mass of 14 kg. What payload margin remains, and is the selection safe based only on static payload?
- 3 A warehouse can choose between a faster robot with poor handling of damaged cartons and a slower robot with better vision and grip adjustment. Explain which system might produce higher real throughput and why.