Today, Amazon has more than 200,000 mobile robots working inside its warehouse network, alongside hundreds of thousands of human workers. This robot army has helped the company fulfill its ever-increasing promises of speedy deliveries to Amazon Prime customers.

“They defined the expectations for the modern consumer,” said Scott Gravelle, the founder and CEO of Attabotics, a warehouse automation startup.

And those expectations of fast, free delivery driven by Amazon have led to a boom in the retail warehouse industry, with entrepreneurs like Gravelle and startups like Attabotics attempting to build smarter and cheaper robotic solutions to help both traditional retailers and younger e-commerce operations keep up with a behemoth like Amazon.