To provide a pipeline shape measurement/evaluation method and its apparatus ensuring sufficient precision even for long-distance measurement by reducing a gravity error caused by a gravity vertical deflection.
With a pig body being in a stationary state, acceleration data of an accelerometer in the stationary state is acquired. From the acceleration data, a gravity direction is determined. From the gravity direction and the latitude of a present position on the ground, an initial attitude angle of the pig body necessary for starting the measurement of the linear shape of the pipeline is calculated. The initial attitude angle is corrected through the use of a correction angle on the basis of the deflection between the gravity direction determined by the acceleration data and a gravity direction when the earth is supposed to be an ellipsoid having a uniform density. Using the corrected initial attitude angle, the linear shape of the pipeline is determined.
NAGAMUNE AKIO
Kiyoshi Yasushima
Souji Sasaki
Noboru Omura
Takanashi Norio