North American demand has surged for autonomous mobile robots (AMRs) in e-commerce, logistics, and retail operations. Because they require minimal infrastructure modifications—unlike fixed automation such as conveyors, sortation, or automated storage and retrieval systems (AS/RS)—AMRs are easy to deploy. They also boost order fulfillment efficiency amid ongoing workforce shortages, improve responsiveness to customer demands, and enhance resilience amid supply chain disruptions.
Warehouses, distribution centers, and fulfillment operations typically deploy one of two different types of AMRs: Goods-to-Person (G2P-AMRs) and Personal Assist (PA-AMRs).
- G2P-AMRs transport items to associates or robotic picking arms for order fulfillment, eliminating walk and search time.
- PA-AMRs support associates as they travel through warehouse aisles, picking needed items like a shopper in the grocery store.
They may seem similar, but the productivity and efficiency gains are very different. Which AMR is best for your warehouse? Here’s a comparison of the two technologies to help you decide.
G2P-AMR and PA-AMR Commonalities
G2P-AMRs and PA-AMRs share many features. These include:
- Safety and navigational systems built with sensors and vision technology. These systems enable safe, autonomous travel throughout an operation.
- Robot control software that integrates with overarching warehouse execution software (WES). The WES assigns tasks to the AMRs and directs their travel along the shortest path.
- Flexibility to expand the fleet with additional AMRs to handle peak volumes or seasonal spikes. Many vendors offer leasing options, further supporting as-needed deployments.
G2P-AMR and PA-AMR Differences
There are several differences between the two types of AMRs. These include:
G2P-AMRs transport goods to associates’ assigned workstations for picking, eliminating the need to walk the aisles. This improves productivity by up to six times over conventional picking methods. Indeed, in some applications that struggle to retain associates, G2P-AMRs have reduced reliance on manual labor by 50%. Conversely, PA-AMRs travel from one picking zone to the next, accepting SKUs selected by associates who walk through the aisles. The PA-AMRs then transport those picks to consolidation or packout areas.
Ability to interface with other automated systems.
G2P-AMRs enable end-to-end automation, as they can retrieve totes from an AS/RS and can support goods-to-robot picking applications, wherein a robotic picking arm (instead of an associate) selects the necessary items from the presented tote. This can raise productivity by an additional 10%, with some operations reporting three times higher picking productivity over manual methodologies. They can also interface with robotic palletizers and automatic stretch wrappers. In contrast, the vast majority of PA-AMRs are designed solely to interface with associates.
Support for different unit loads and picks.
G2P-AMRs generally feature heavier-duty, more robust construction than PA-AMRs. This allows them to handle a variety of different unit load types, such as individual totes for each picking, full pallet loads for case picks, or multi-tiered shelving units with different items for case or each picking. Typically engineered to carry lighter loads, PA-AMRs generally support only each picking.
Storage density improvement.
G2P-AMRs facilitate higher-density storage by traveling in areas that do not need to accommodate personnel. They easily navigate amid tightly packed storage shelves or pallets, or they retrieve totes of inventory from an AS/RS. Unlike PA-AMRs, no aisles are required for forklifts or pallet jacks. This can increase a facility’s space efficiency by an average of 20%.
Integration into different workflows.
Beyond picking, G2P-AMRs can also be deployed to support different inventory handling processes. They can assist with receiving, put away, forward-pick replenishment, staging, buffering, and consolidation of orders. PA-AMRs typically only support conventional picking methodologies.
While both offer flexibility and scalability advantages over fixed automation—and improve picking efficiency by reducing travel while enhancing order fulfillment accuracy—G2P-AMRs and PA-AMRs are ideal for different applications.
PA-AMRs are a small step away from conventional, paper-based picking without significant process changes. In contrast, G2P-AMRs dramatically reduce labor dependence by eliminating the need for associates to travel to picks. By delivering the required SKUs to pickers (or robotic picking arms) at workstations, far fewer employees can fill the same (or more) number of orders much faster than conventional picking. G2P-AMRs also boost storage density.
Perhaps that’s why G2P-AMRs led the autonomous mobile robot technology market in investments in 2022, representing more than 48% of global share.
Want to Learn More?
Download our whitepaper, which compares Goods-to-Person and Person Assist AMRs, for a deeper dive into these technologies and their optimal applications.