Inc. sold more than 175 million products across the globe during its 48-hour Prime Day sales event a few weeks ago — more than Black Friday and Cyber Monday combined. More than 10 million items qualified for next-day delivery. Making that happen depends on robots.

"Speed is the name of the game right now," said Aaron Meyers, senior operations manager at Amazon's four-story fulfillment center in Shakopee, during a recent tour. "The technology allows us to be a lot more safe and efficient, and to get product to our customers much faster."

To meet consumers' growing appetite for e-commerce and fast delivery Amazon is increasingly relying on robotics and advanced technologies such as artificial intelligence, machine learning and computer vision.

The warehouse and shipping center, which opened almost exactly three years ago in the southwestern Twin Cities suburb, is one of at least 25 robotic fulfillment centers in the U.S. and more than 50 worldwide. It is central to executing Amazon's same-day shipping strategy in Minnesota and the region.

Robots unload merchandise from trailers, move inventory around warehouses and sort packages to the proper ZIP codes. Worldwide, Amazon has installed more than 200,000 robots, officials said last month at a trade show in Las Vegas.

The aim, said Amazon spokeswoman Brenda Alfred, is to "make mundane, tedious and arduous tasks easier and more efficient, allowing our skilled associates to reallocate their abilities to more sophisticated tasks where the can add the most value."

At the Shakopee facility, robots that look like bright orange mini race cars muscle around tens of thousands of tall shelving units that are lined up as far as the eye can see.

Amazon engineers named the robots Hercules — or H Drive — because they can lift pods holding about 1,250 pounds worth of merchandise.

The robots can scoot across 5 feet of warehouse space in a second, swiftly delivering a pod to a worker who picks out the item and starts the process of getting it out the door not long after the customer clicked the "buy" button.

Now in its second generation, there are 100,000 of these nearly 8-inch high robots working at Amazon fulfillment centers worldwide.

The sleeker design makes the robots easier to build and maintain. But it also allows the company to squeeze more pods of inventory.

Amazon estimates that the robotics system has enabled it to store up to 40% more inventory than at a traditional warehouse while lessening strain on workers' bodies, who can walk 10 to 15 miles a day plucking merchandise off shelves.

The robots navigate using a grid of bar codes. But occasionally merchandise drops out of the pods, or the robots stall or need to be rebooted.

New safety vests worn by what Amazon calls the "amnesty team" use artificial intelligence and sensors to allow the workers and robots to work together.

Workers put on the safety vest when they need to step onto the robotics floor, which both slows down the robots and then reroutes them.

The process barely skips a beat. More than 1,000 of the vests are being used.

"The vest technology puts a giant bubble around them," Meyer said. "It slows the pods down to a crawl because it knows exactly where the associate is on the floor."

Yet even as Amazon adds more automation, the unrelenting push to pick, pack and ship more items at a faster pace has been a flash point issue for the retailer's employees.

Muslim workers in Minnesota have made national headlines over their protests. Presidential candidate Sen. Bernie Sanders is seeking an investigation from the Occupational Safety and Health Administration (OSHA).

The tension between the need for human labor and automation of tasks remains ever-present in the digital age in all types of industries.

A 2017 report by McKinsey Global Institute estimated that automation could displace up to 800 million people globally by 2030, though automation and technology also create jobs.

Fear among workers is palpable. A survey by the Pew Research Center found that roughly half (48%) of respondents said the advances have mostly hurt American workers; only 22% said they have generally helped.

A fully automated shipping warehouse is at least a decade away, Amazon officials have said, but the company already is planning for a time when it will need fewer people to run its warehouses.

Earlier this month, Amazon announced that it would set aside $700 million between now and 2025 to "upskill" or retrain up to a third of its U.S. workforce — as many as 100,000 workers.

Amazon's Alfred said that, historically, the acceleration and growth of robotics and automation have led to more jobs across several industries.

With increased productivity often comes increased consumer demand, she said, and the ability to reinvest in new services for customers.

"In the long term," Alfred said, "this means continued job growth and a new sector emerging of warehouse environments in which employees work in technologically rich environments."

Jackie Crosby • 612-673-7335