PORTABLE TERMINAL, PROGRAM, AND METHOD OF DETERMINING A VERTICAL DOWNWARD DIRECTION DURING WALK BY UTILIZING TERRESTRIAL MAGNETISM

摘要

PROBLEM TO BE SOLVED: To provide a portable terminal capable of more accurately determining vertically downward acceleration even when a walker carries a portable terminal in a pocket of trousers and so on.SOLUTION: A portable terminal includes: an acceleration sensor and a terrestrial magnetism sensor; standstill acceleration direction determination means of determining a standstill acceleration direction when a standstill on terminal coordinate system is determined; terrestrial magnetism vertical component determination means of determining a terrestrial magnetism vertical component Mas a projection component of the terrestrial magnetism vector M at the standstill determination time to a standstill acceleration direction; terrestrial magnetism projection component calculation means of calculating a terrestrial magnetism projection component Mas a projection component of a terrestrial magnetism vector M at each point of time to the standstill acceleration direction; vertical standstill time point determination means of determining a vertical standstill point of time as a point of time when it can be determined that standstill acceleration vertically faces down by comparing the calculated terrestrial magnetism projection component Mand the determined terrestrial magnetism vertical component Mwith each other.