Analysis of rolling motion effect on SINS error modeling in PIG

When the Pipeline Inspection Gauge (PIG) is driven by the pressure differential between its two ends, the motion of the PIG inside the inspected pipeline is mainly dominated by the rotation motion around its longitudinal axis (rolling) and the conventional travelling motion along the pipeline longitudinal direction. The rolling motion improves PIG's capability to go through some heavy sludge or wax obstacle areas in the bottom part of the pipeline and enhances the inspection capability for the potential defects inside the pipeline. Moreover, it has some positive effects on the Strapdown Inertial Navigation System (SINS) error model and the corresponding localization precision. This paper presents an innovative error modeling technique, which is based on the detailed analysis of the Micro-Electro-Mechanical System (MEMS) inertial sensors main error sources (gyroscope biases and scale factor errors, accelerometer biases and scale factor errors) on SINS error model when the PIG is exhibiting the rolling motion. The developed error models were verified experimentally at different rolling rates. Results showed high consistency with the theoretical analysis conclusions.