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%.