RFID + Camera + Lock = Smart Mailbox

New mailbox hardware applies to become your home's watchdog

3 min read
Interior view of smart mailbox with hardware components
The picture of the door shows the RFID reader (on the left) and the solenoid lock (on the right).
Photo: Jonathan Ross Tew

A self-locking mailbox could someday flag down delivery drones and intelligently screen your driveway for intruders.

Columbus State University computer scientist Lydia Ray presented the technology, called the ADDSMART project, during a 20 October session at the annual IEEE Ubiquitous Computing, Electronics, and Mobile Communication Conference in New York City.

The project aims to achieve two goals: clearly marking addresses for autonomous vehicles, and reducing the energy and data storage costs of home surveillance systems. An early prototype mailbox attachment suggests that the trick, in both cases, may be radio-frequency identification.

Powered by an Arduino Yun processor, one component of the ADDSMART device controls a high-frequency 13.56-MHz RFID reader, USB camera, passive-infrared motion sensor, solenoid lock, and an onboard Wi-Fi module. The second component is an RFID tag. 

Ray came up with the idea when she saw an Amazon ad for drones delivering packages. She wondered how that would be possible, as some of her regular mail still arrives at the wrong address.

In the United States, Amazon and Google and startups such as the Reno, Nev.–based Flirtey, are trying delivery via drones. One of a drone’s challenges is to home in on its destination. But accurately identifying addresses with standard GPS alone is really difficult, Ray says, because GPS uses latitude and longitude. The GPS sensor is good for identifying a location—but an additional system is needed for pinpointing a precise address.

Some approaches for tackling the location problem include computer vision techniques with cameras. Ray points out that even identifying addresses with human vision can be hard. At her house, the address is written on the pavement and “is not easily identifiable.” Then, Google Street View, which updates infrequently at best, doesn’t show that her neighbor’s house recently changed colors; and it wouldn’t even work so well for finding an address at night.

With an RFID tag on a home’s mailbox and an RFID reader on a drone or car, Ray believes that the delivery process could become relatively easy. The drone would use GPS to navigate to an address and then confirm that the address is correct by checking the RFID tag.

Once Ray decided to attach an RFID tag to a mailbox, she realized that RFID can do more than flag down drones: it offers security, too. An RFID-reader-equipped system could store a list of “safe” RFID tags whose possessors would be able to pass by a home or open the mailbox unimpeded. 

Instead of a home surveillance system continuously checking for intruders, a video camera could save energy by starting to record only when an unrecognized vehicle or person passes the mailbox. The mailbox could also unlock when authorized users—such as a homeowner or mail carrier—arrive.

After soldering and wiring the necessary hardware for the smart mailbox and writing computer scripts for running commands, Ray and her student, Jonathan Ross Tew, tested the sensors indoors and outdoors. 

When the motion sensor detected a change in passive infrared radiation—a type of electromagnetic radiation given off by anything warmer than about -270°C—the USB camera took a picture. Computer scripts sent the picture via email to a recipient and uploaded it to Dropbox.

Also, when an RFID tag was in the RFID reader’s limited detection range, the system checked whether the tag was marked with the homeowner ID or postman ID. In either case, it would open the solenoid lock, but the postman tag also triggered an email alert.

Ray said the passive-infrared motion sensor the team used pretty much failed outdoors—there were 931 false positives out of 937 tries. Using a more expensive sensor could help, she said.

Future work includes testing the system under various conditions and investigating the total area of surveillance coverage, technical interference with nearby smart mailboxes (like this Kickstarter project, Mr. Postman), security, and privacy.

So how will smart mailboxes flag down drones in apartment and condo complexes with cluster mailboxes? Ray told IEEE Spectrum that each individual mailbox could have its own RFID tag with an apartment number or post box number for flagging down drones. As for the surveillance function, Ray says a monitoring system similar to the one used in the prototype could monitor the door of each apartment.

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