Walmart is testing a system that uses autonomous carts to retrieve refrigerated and frozen items ordered for online grocery. The aim is to enable quicker, more efficient picking of online grocery orders at the store level. The Alphabot system operates inside a 20,000-sq.-ft. warehouse-style space. After it retrieves the products, Alphabot delivers them to an in-store workstation, where a Walmart associate checks, bags and delivers the final order, according to Chain Store Age.