Small Pipeline Trajectory Estimation Using MEMS Based IMU

H. Sahli, A. Moussa, A. Noureldin, and N. El-Sheimy

Abstract:	Advances in Micro-Electro-Mechanical-Systems (MEMS) technology combined with the miniaturization of electronics, have made it possible to produce low cost and lightweight chip-based inertial sensors. These chips are small, lightweight, consumes very little power, and reliable. It has therefore found a wide spectrum of applications in the automotive and other industrial applications. MEMS technology, therefore, can be used to develop navigation systems that are inexpensive, small, and consume low power (microwatt). However, the current achieved performance by these low cost sensors is relatively poor due to their sensor errors. Nowadays, high-end tactical grade Inertial Measurement Units (IMUs) are used in pigging applications for estimating the trajectory of geo-pigs in pipelines. These types of IMUs are accurate enough to provide an acceptable solution. However, the size of the tactical grade IMUs is large and cannot be used in the small diameter pipelines (8” or less). This paper investigates the potential of MEMS-IMUs for positioning of the Pipeline Inspection Gauge (PIG) for small pipelines even during the unavailability of Above Ground Markers (AGM) which are typically used in current PIGs operation. Integrating MEMS-IMUs with alternative sensors has the potential of providing significant performance improvement. Odometer is a complementary sensor that is commonly used to provide simple but incomplete and inaccurate position information. It can only measure distances and is subjected to unbounded cumulative errors. Extended Kalman Filter (EKF) is the commonly used technique for multi-sensor integration in navigation applications. Furthermore, EKF backward smoothing algorithms can be applied to post-process the data. EKF smoothing can result in significant performance improvements especially for low cost INS integration. In this paper, multi-sensor data fusion system is implemented with three main sensor types, namely MEMS-IMUs, odometer and Above Ground Marker (AGM). In order to improve the performance of integrated navigation system, non-holonomic constraints are considered and the navigation system is modeled as a linearized dynamic system. The performance of the proposed method is examined using real pipeline data that has been obtained using MEMS-IMU. The results obtained in this paper show that the system is capable of meeting the performance requirements for pipeline operators with a reduced number of AGMs (e.g. RMSE of the trajectory did not exceed 2.3m over 1 hour of operation and with one AGM along the PIG journey).
Published in:	Proceedings of the 27th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2014) September 8 - 12, 2014 Tampa Convention Center Tampa, Florida
Pages:	154 - 161
Cite this article:	Sahli, H., Moussa, A., Noureldin, A., El-Sheimy, N., "Small Pipeline Trajectory Estimation Using MEMS Based IMU," Proceedings of the 27th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2014), Tampa, Florida, September 2014, pp. 154-161.
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