To allow an initial orientation to be calculated even when a position calculation device does not come to a standstill.
When detecting that an acceleration value which is magnitude of an acceleration vector measured by an acceleration sensor 10 reaches a value corresponding to gravitational acceleration during movement, a position calculation device 1 sets an orientation calculated from the acceleration vector at that time to a reference orientation. Further, thereafter, the position calculation device 1 calculates the orientation of the position calculation device 1 by integrating the reference orientation with an angular velocity vector measured by a gyro sensor 20 by means of time integration. Furthermore, the position calculation device 1 calculates a position of the position calculation device 1 by using the acceleration vector and the orientation calculated.
Takekoshi Noboru
Inoue Ichi
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