Thursday, November 08, 2007

Random-Access Warehouses

A company called Kiva Systems is speeding up Internet orders with robotic systems that are modeled on random-access computer memory.

By Kevin Bullis

Little laborers: Dozens of simple robots (above), paired with smart, adaptable algorithms, speed up deliveries of online orders. The robots carry shelves to workers, who collect items for shipping. Credit: Paul Avis, Kiva Systems (top) Kiva Systems (bottom)

Multimedia •  See the robots in action.

Squat orange robots and a set of adaptive algorithms are making it possible to deliver online orders faster. The system, so far installed in two giant Staples warehouses, allows workers to fill two to three times as many orders as they could with conventional methods. The startup that developed the robots and software, Kiva Systems, based in Woburn, MA, announced yesterday that it is rolling out a third system, for the pharmacy giant Walgreens.

Kiva Systems' CEO and founder, Mick Mountz, likens the system to random-access memory chips. The warehouse is arranged in a memory-chip-like grid composed of rows and columns of freestanding shelves. The grid gives robots access to any product in the warehouse at any time. The robots serve two basic functions. First, they deliver empty warehouse shelving units to workers who stock them. The workers might stock one unit with a mix of paper, various types of pens, and computer software, all compiled from large pallets that had been delivered to the warehouse. Then, 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. "We turn the whole building into a random-access, dynamic storage and retrieval system," Mountz says.

If a consumer orders an item at 2 P.M. on a Thursday, he says, at 2:01, a robot can be delivering that order to a worker to pack. If an order has multiple items, robots will line up for workers as fast as the workers can pack the items. Once the items are packed, robots can pick up the boxes, storing them temporarily or delivering them to the appropriate delivery truck.

Mountz says that the system allows workers to fill orders much faster than conventional systems do because the robots can work in parallel, allowing dozens of workers to fill dozens of orders simultaneously. In one type of conventional system, workers have to walk from shelf to shelf to fill orders, and all that walking takes time. With the Kiva system, several robots can be dispatched to collect all the items in an order at once. The robotic system is also more efficient than conveyor-based systems, in which elaborate conveyors and chutes send boxes past workers who pack them as they go by. In such a system, the slowest part of the line, which could be the slowest worker, limits the overall speed. With the help of the robots, each worker fills an entire order, so one worker doesn't slow everyone else down.

The robotic system is also faster because the entire warehouse can adapt, in real time, to changes in demand. Robots move shelves with popular items closer to the workers, where the shelves can be quickly retrieved. Items that aren't selling are gradually moved farther away. More-conventional warehouses can also be adaptive, Mountz says, but it takes much longer to rearrange items.

A schematic of a warehouse floor. Shelves with fast-selling items are indicated in red. Blue squares show slow-selling items. Robots rearrange the shelves to keep the fast-selling items at the perimeter, close to packing stations.
Credit: Kiva Systems