Testing and evaluation of an inertial/magnetic sensor-based pen input device

Testing and evaluation of a novel pen input device are presented in this paper. The pen input device could be used to write on any type of surface including desktops, blackboards, or in the air. It is constructed by attaching an inertial/magnetic sensor module to a writing instrument such as a pencil, a marker, or a piece of chalk. The inertial/magnetic sensor module has three accelerometers, three angular rate sensors, and three magnetometers. A tracking algorithm and a calibration algorithm are described. The tracking algorithm is for estimating the pen tip trajectories based on the sensor measurements, and the calibration algorithm is for estimating the relative position of the sensor module on the writing instrument. Experimental results for writing alphanumeric characters are presented. The relationship between tracking accuracy and writing speed is also discussed.