Thermal Calibration of Low Cost MEMS Sensors for Integrated Positioning, Navigation Systems

Global Positioning System (GPS) provides reliable long term navigation information but requires a direct line of sight between the GPS receiver and the GPS satellites. On the other hand, an Inertial Measurement Unit (IMU) offers continuous autonomous solution but the accuracy cannot be guaranteed for long period of time as the errors accumulate due to the integration of its signals. The integration of GPS long-term and accurate information with the continuous but short-term accuracy of IMU systems should be able to provide accurate and uninterrupted navigation system for many difficult navigation scenarios. Micro Electro Mechanical System (MEMS) inertial sensors offer a solution for low cost land vehicle navigation applications. However, being small in size and light in weight, MEMS sensors experiences more errors like turn-on biases or scale factor errors which are generally smaller or negligible for other higher grade inertial sensors. Moreover MEMS sensors are highly dependent on environmental conditions specially temperature. This paper proposes a thermal compensation model to accurately sense bias and scale factor changes with temperature for MEMS sensors. In addition to conducting lab calibration to obtain this thermal model, lab and field compensation tests are performed to validate the proposed research.