Wearable handwriting input device using magnetic field: 2nd report: Influence of misalignment of magnet and writing plane

In the past we proposed a wearable handwriting input device using magnetic field. This device requires mounting a permanent magnet onto the user's fingertip and operates by detecting the magnetic field generated by the magnet through two magnetic sensors attached at the wrist of the other hand. The position of the magnet is calculated by the vector of the magnetic field. The calculation assumes that the magnetic axis rests on a plane where the sensors lie, perpendicular to the vector formed by the two sensors. In this paper we study the level of error that may arise when this assumption is violated, by investigating four possible misalignments (two kinds of rotations of the magnet and two ways of positioning the writing plane) with comparing the result of experiment and simulation. We conclude that misalignment due to a z-axis rotation is non-negligible and is best avoided during usage.