PURPOSE: To reduce a detection error, by deriving an offset by average-processing for an angular velocity turning round an X axis when installing an angle sensor in the X axis direction, subtracting the result from a signal by an angular velocity turning around a Z axis, and executing its integral processing.
CONSTITUTION: In case when a prescribed direction on the horizontal plane and a vertical direction of a vehicle are set as an X axis and a Z axis, respectively, angular velocity sensors 12, 13 are made to move its installing direction alternately by a prescribed timing due to a time factor in the X axis direction and the Z axis direction. When installing in the X axis direction, an offset is derived by executing average-processing of an angular velocity signal from the angular velocity sensor. When installing in the Z axis direction immediately after it, an angular velocity turning around the Z axis is derived by subtracting the offset from the angular velocity signal fed from the angular velocity sensor. Subsequently, the offset is updated successively in its time by integral-processing this derived angular velocity by a microcomputer 39 so that a running bearing of the vehicle is derived.
OGAWA KOUJI
KATOU KENJI
KOSUGE SHIYUUICHI
