The Seattle Times reports that the patent, granted by the US Patent and Trademark office in 2016, depict a cage-like enclosure surrounding a small office space, and was described by researchers last Friday as "an extraordinary illustration of worker alienation, a stark moment in the relationship between humans and machines." 

Amazon in 2016 was granted a patent for a system to transport humans, enclosed in a cage and on top of a robotic trolley, for work in areas full of other automated robots. (U.S. Patent and Trademark Office)

That said, Amazon says they never implemented the cage system and has no plans to do so, however the design looks to be an effort to allow human workers to safely integrate with dangerous robot-only zones in the Seattle company's highly-automated warehouses.