When is Where
Inspired by the location-based magic of Harry Potter and the confluence of time and space in Clive Barker’s Abarat, from which it draws its name, Where is When provides a novel interface for presenting location data.
Rather than numbers, the face of the clock displays place names (in this case, rooms at ITP), and features a single hand which points to the location of the user in question. There is a button on the side of the clock, which allows the user to be paged. When the button on the clock is pressed, each of the remote boxes, located in one of the designated rooms glows amber, signaling that someone is attempting to locate the user. To signal his location, the user presses the button on the face of the box, which moves the hand on the face of the clock to the correct position and turns off the paging lights on all remote boxes.
This is an early prototype to demonstrate one method of using wireless-enabled microcontrollers to track location. It was developed using Arduino boards and using the Atmel ATMega8 controller and XBee 802.15.4 wireless devices. The clock features an XBee Pro, while the remote boxes are using standard XBees. In the current version, the XBees are being used as a serial bridge between the controllers, with single bytes of data being sent on every button press, either signaling a page, a location, or an all-clear.
This setup yields a wireless range of about 100-150 feet. The next step will be to upgrade the XBees with the ZigBee standard to enable mesh networking, which is ideally suited to this setup. Obviously, location tracking is best when done automatically, and I’m experimenting with using the XBees themselves to provide data on where in the building a wearable unit is located. Unlike RFID, which would require an expensive reader in every room, the XBees may provide a method that’s both low cost and low power for simple location tracking. And because of their flexibility when paired with a microcontroller, providing a rich two-way communication between the observer and the observed will be possible.
As a nod to the Weasley’s clock in Harry Potter, the 6 o’clock position reads “mortal peril”, but because of the servo motor used in the prototype, it’s not actually possible for the clock to ever proclaim that I’m in mortal peril. Due to a quirk in programming, an early version was also unable to designate that I was at home, which is fairly accurate.
Thursday, November 2, 2006
