Abstract: A pipeline surveying system including a pipeline pig can accurately provide a pipeline profile after correlation with a previously determined GPS survey. An inertial measurement unit located in the pig determines a pipeline profile as it travels through the pipeline and correlates the measured profile with the GPS survey.

Abstract: A pipeline surveying system including a pipeline pig can accurately provide a pipeline profile after correlation with a previously determined GPS survey. An inertial measurement unit located in the pig determines a pipeline profile as it travels through the pipeline and correlates the measured profile with the GPS survey.

Abstract: A pipeline surveying system including a pipeline pig can accurately provide a pipeline profile after correlation with a previously determine Global Positioning System (GPS) survey. An inertial measurement unit located in the pig determines a pipeline profile as it travels through the pipeline and correlates the measured profile with the GPS survey.

Abstract: A pipeline inspection and defect mapping system includes a pig having an inertial measurement unit and a pipeline inspection unit for recording pig location and defect detection events, each record time-stamped by a highly precise onboard clock. The system also includes several magloggers at precisely known locations along the pipeline, each containing a fluxgate magnetometer for detecting the passage of the pig along the pipeline and further containing a highly precise clock synchronized with the clock in the pig. The locations of the various magloggers are known in a north/east/down coordinate system through a differential global positioning satellite process. Finally, a postprocessing off-line computer system receives downloaded maglogger, inertial measurement, and odometer data and through the use of several Kalman filters, derives the location of the detected defects in the north/east/down coordinate frame. Consequently, a task of identifying sites for repair activity is much simplified.

Abstract: A pipeline distortion monitoring system equipped with an inertial system measures geometric characteristics of the pipeline, and generates signals representative of the characteristics. Additional sensor means are used to aid in correcting the signals. Corrected signals along with other characteristics yield pipeline profile characteristics used to assess pipeline distortions.

Abstract: A sensor assembly along with numerous processing equipment is provided for attachment to the work table of a precision machining system. By attaching the device to the work table and subsequently driving the work table through a repeated pattern of motions, the actual movement of the table can be precisely determined and, consequently, can be compensated for. The sensor assembly utilizes a plurality of gyroscopes and accelerometers to determine actual movement in inertial space.

Abstract: Inertial sensor information is combined with GPS information derived from satellite information signals separately received by a pair of GPS antennae and separately processed. This information is processed in a manner to arrive at the offset angle between the inertial sensor heading angle and true north.

Abstract: In a dithered ring laser gyro, a dither reference signal is provided to supply information representative of the dither angle or dither angular rate. This information is processed by a signal processor to generate a correction signal which is the sum of (i) a first function of the dither reference signal indicative of the dither angle multiplied by a first coefficient, and (ii) a second function of the dither reference signal indicative of the dither angular rate multiplied by a second coefficient. The aforementioned coefficient may be either selected or generated based on historical data derived from the dither reference signal and the usual sensor output signal. In turn, the correction signal is subtracted from the usual ring laser gyro output signal to provide a corrected sensor output signal.