Amazon.com Inc. (Nasdaq: AMZN), Google Inc. (Nasdaq: GOOG) and Wal-Mart Stores Inc. (NYSE: WMT) are testing drones for inventorying warehouses, curbside pickup and home delivery, and waiting for U.S. regulators to weigh in on commercial use of unmanned aircraft systems.

In the meantime, grounded robots are becoming increasingly ubiquitous in warehouses and factories, where they provide several advantages over human laborers. For instance, robots are able to take on tasks that are too dangerous for humans. Robots can also operate for extended periods of time without getting tired, freeing owners of the need to provide breaks, overtime and raises.

Amazon is among the leaders. The e-commerce pioneer bought Kiva Systems Inc. for $775 million in 2012. Kiva is now part of Amazon Robotics, which has ambitious plans for autonomous mobile robots that will incorporate language perception and machine learning.

A handful of companies acquired robot manufacturers in 2015. The list includes Bubble Wrap owner Sealed Air Corp. (NYSE: SEE), which has plans to buy French company B+ Equipment, a maker of automated packaging equipment. Japan’s Omron Corp. is paying $200 million for Adept Technology Inc. (NASDAQ: ADEP). Adept makes mobile robots that are used to make packaging processes quicker. Teradyne Inc. (NYSE: TER) completed its $285 million acquisition of Universal Robots, which supplies robots that work alongside manufacturing workers. And Omnicell is paying $275 million to buy Aesynt, which makes medicine-dispensing robots, from Francisco Partners.