GyroPen: Gyroscopes for Pen-Input With Mobile Phones

We present GyroPen, a method to reconstruct the motion path for pen-like interaction from standard built-in sensors in modern smartphones. The key idea is to reconstruct a representation of the trajectory of the phone´s corner that is touching a writing or drawing surface from the measurements obtained from the phone´s gyroscopes and accelerometers. We propose to directly use the angular trajectory for this reconstruction, which removes the necessity for accurate absolute 3-D position estimation, a task that can be difficult using low-cost accelerometers. We connect GyroPen to a handwriting recognition system and perform two proof-of-concept experiments to demonstrate that the reconstruction accuracy of GyroPen is accurate enough to be a promising approach to text entry. In a first experiment, the average novice participant (n=10) was able to write the first word only 37 s after the starting to use GyroPen for the first time. In a second experiment, experienced users (n=2) were able to write at the speed of 3-4 s for one English word and with a character error rate of 18%.