The robot invasion may soon be coming to a warehouse near you. In a conventional warehouse, workers walk from shelf to shelf to fill orders, while in conveyor-based systems, boxes move past workers who pack them. A new warehouse design arranges rows and columns of freestanding shelves in a memory-chip-like grid serviced by robots. When a consumer submits an order, robots deliver the relevant shelving units to workers who pack the requested items in a box and ship them off allowing workers to fill orders two to three times faster than they could with conventional methods because the robots can work in parallel, allowing dozens of workers to fill dozens of orders simultaneously. The robotic system is also faster because the entire warehouse can adapt, in real time, to changes in demand by having the robots move shelves with popular items closer to the workers (pdf), where the shelves can be quickly retrieved while items that aren't selling are gradually moved farther away. Two giant warehouses have already been built for Staples and a third is being built for Walgreens where the software will also keep track of expiration dates to ensure that items that can go bad are sent out in the order that they're stocked.