To make motion gestures more widely adopted on mobile devices it is important that devices be able to distinguish between motion intended for mobile interaction and every-day motion. In this paper, we present DoubleFlip, a unique motion gesture designed as an input delimiter for mobile motion-based interaction. The DoubleFlip gesture is distinct from regular motion of a mobile device. Based on a collection of 2,100 hours of motion data captured from 99 users, we found that our DoubleFlip recognizer is extremely resistant to false positive conditions, while still achieving a high recognition rate. Since DoubleFlip is easy to perform and unlikely to be accidentally invoked, it provides an always-active input event for mobile interaction.

Jaime Ruiz and Yang Li. 2011. DoubleFlip: a motion gesture delimiter for mobile interaction. In Proceedings of the SIGCHI Conference on Human Factors in Computing Systems (CHI '11). ACM, New York, NY, USA, 2717-2720.

 author = {Ruiz, Jaime and Li, Yang},
 title = {DoubleFlip: A Motion Gesture Delimiter for Mobile Interaction},
 booktitle = {Proceedings of the SIGCHI Conference on Human Factors in Computing Systems},
 series = {CHI '11},
 year = {2011},
 isbn = {978-1-4503-0228-9},
 location = {Vancouver, BC, Canada},
 pages = {2717--2720},
 numpages = {4},
 url = {},
 doi = {10.1145/1978942.1979341},
 acmid = {1979341},
 publisher = {ACM},
 address = {New York, NY, USA},
 keywords = {mobile interaction, motion gestures, sensors},