We haven't heard too much from Google's Project Wing, the company's drone delivery project, but a patent filing first reported by Fast Company today suggests the team is hard at work figuring out to get a fleet of robots to work together to automate package drop offs. The patent, filed in October 2014 and granted just yesterday, describes a system by which an aerial drone would communicate with a robotic "mobile delivery receptacle" — a box with wheels — so a package could be delivered in a safe location and then ferried to a secure drop off point.

The box would use infrared to flag down the drone to receive the package and would most likely contain a locking mechanism to prevent people from snatching objects before they're brought to the holding location. The secure spot could be a public pickup point perhaps similar to an Amazon Locker, a place for local delivery companies to grab packages and bring them to your door, or somewhere on a private residence like a garage. Google says this should alleviate concerns such as the drone injuring pets and destroying property or the package being stolen from someone's porch. "Conventional aerial delivery methods do not allow for safe, secure delivery of packages to delivery locations," the patent explains.

Aerial drones working together with robot boxes on wheels

Although it's just a patent, this potential delivery strategy marks Google's most concrete outline of a drone-based delivery network to date. Project Wing head Dave Vos told said in October his team wanted to launch the service in 2017, which is an ambitious time frame putting Wing head to head with Amazon's own Prime Air drone delivery project. Of course, Google has a handful of robotics companies at its disposal after a series of secretive acquisitions in 2013, so it's not outside the company's wheelhouse to try and pair grounded robots with ones in the sky.