MagID: Enhancing the Functionality of Off-the-Shelf Smartphones Through Magnetic Accessory Identification

Abstract

Since the release of MagSafe, which allows magnetic attachment of accessories to smartphones, many vendors have introduced various kinds of MagSafe accessories, including wireless chargers, wallets, car mounts, and coolers. In light of this trend, we introduce MagID, a novel interface to connect physical accessories with software functionalities. For example, when an accessory (e.g., a car mount) is attached, it automatically invokes a specific application (e.g., a navigation app) or performs a certain task that corresponds to the accessory. The main idea of MagID for supporting this functional connection is to identify when and which accessories are attached to or detached from a smartphone. More specifically, based on our observations that MagSafe accessories have different magnetic properties from each other, we design a magnetic sensing-based accessory identification method and further improve its robustness with the combined use of non-magnetic features, e.g., accelerometer, gyroscope, and battery state readings. Our extensive experiments with a prototype implementation of MagID demonstrate that MagID can identify MagSafe accessories with high accuracy on any MagSafe-enabled smartphone and even in noisy environments, while not compromising usability.