At this Walmart, humans and robots work together to fill your grocery orders

A Walmart employee waited for filled carts in Salem, N.H.Suzanne Kreiter/Globe staff/Globe staff

SALEM, N.H. — Walmart is betting that online grocery shopping will be so popular someday that its workforce will have a hard time keeping up with all the orders. So here come the robots.

The giant retailer has teamed up with Alert Innovation, a robotics engineering firm in North Billerica, to build a “micro-fulfillment center” — a 20,000-square-foot, semi-automated miniature warehouse — alongside the Walmart Superstore in Salem. Inside a large, windowless concrete cube, humans and robots work together to quickly pick and pack thousands of grocery items that were ordered online, and trundle them outside to shoppers waiting in their cars.

The system is called Alphabot. It uses small wheeled robots that roll along long steel rails, surrounded by shelves containing plastic bins. Each bin holds some commonplace item — mustard, taco seasoning, pistachio nuts, and so on. There’s a refrigerated section, so customers can order chilled or frozen foods.

The shelves are about as long as a basketball court and three stories high. Each robot has geared wheels that let it climb up or down through horizontal shafts. When it reaches the right level, the robot rolls up to the correct bin, plucks it from the shelf, then descends to a packing station. The robot passes the bin to a Walmart worker who picks out the correct item and plops it into a different bin lined with standard grocery bags.

When the order is complete, a robot grabs the bin and shuttles it over to a station where a worker puts it on a cart and wheels it away.

It may seem futuristic, but according to John Lert, founder of Alert Innovation, his system in part evokes an earlier era: 100 years ago, a grocery shopper would tell a clerk what he wanted, and the clerk would go out back to fetch it.

The idea of a big store where shoppers themselves pick the items was pioneered by the Piggly Wiggly retail chain in 1916. For a century, it has worked just fine, and not just for consumers. Self-service worked for retailers, too, by reducing the need for clerks, thereby keeping labor costs in check.

Enter the Internet, which makes it easy to shop without setting foot in a store. Just place your order and pick it up. Only one problem: Companies need additional workers just to collect and pack all of those incoming orders.

“Paying people to do what customers do for free, without raising prices, is a nonsustainable business model,” Lert said.

Besides, said Brian Roth, Walmart’s senior manager of pickup automation, all those clerks collecting pickup orders clog the aisles and obstruct other shoppers. By installing Alphabot, “we’re kind of transitioning some of that congestion from the sales floor into the back room,” he said.

Walmart began working with Lert on the Alphabot concept in 2016 and began filling orders using the robots last March. But Walmart said it will go slow on expanding Alphabot as it learns more about how the robot system is working. Right now in Salem, robots handle only 20 percent of the store’s online orders. The company plans to next deploy Alphabot at stores in Mustang, Okla., and Burbank, Calif.

Walmart and Alert Innovation face plenty of competition.

Ahold Delhaize, parent company of the supermarket chain Stop & Shop, has deployed a similar system designed by another Massachusetts company, Takeoff Technologies of Waltham. Another major grocer, Albertsons, is also working with Takeoff.

Other automation companies in the mix include Georgia-based Dematic, the Israeli company Fabric, and the United Kingdom’s Ocado Group, which has teamed up with the big US retailer Kroger.

“Everybody’s doing this, not just Walmart,” said Barry Friends, a partner at Pentallect, a food industry consulting firm in Chicago.

And everybody’s doing it, Friends said, because online grocery ordering is looking like the next big thing. For now, it’s only a sliver of the total US market — worth about $20 billion last year, according to the research firm eMarketer. But it’s the fastest-growing segment of online retailing in the United States, with an expected growth rate of 18 percent each year.

“It still is very small as a percentage of the whole pie,” Friends said, “but it’s growing quickly.”

And most of the growth doesn’t come from home delivery. Friends said consumers have fallen in love with online ordering and pickup, or “click-and-pick” services.

“It’s super-popular with working mothers,” he said, because the kids stay buckled up in the back seat. ”Thousands of stores have spent millions of dollars” on remodelling to make room for drivers to pick up their orders.

The Salem store’s pickup zone is about a block long — plenty of room for impatient consumers to grab their orders and go.

And though the Alphabot system currently uses 30 robots to distribute about 4,500 items, Lert said it’s capable of handling up to 100 robots and contains enough space for 20,000 items.