| 摘要 |
<p>A pipeline inspection and defect mapping system includes a pig (300) having an inertial measurement unit (306) and a pipeline inspection unit (312) for recording pig location and defect detection events, each record time-stamped by a highly precise onboard clock (314). The system also includes several magloggers (200) at precisely known locations along the pipeline, each containing a fluxgate magnetometer (202) for detecting the passage of the pig (300) along the pipeline and further containing a highly precise clock (204) synchronized with the clock (314) in the pig. The locations of the various magloggers (200) are known in a north/east/down coordinate system through a differential global positioning satellite process. Finally, a postprocessing off-line computer system (400) receives downloaded maglogger (804), inertial measurement (806 and 808), and odometer data (802) and through the use of several Kalman filters (830), derives the location of the detected defects in the north/east/down coordinate frame.</p> |
