Use of a MEMS accelerometer to measure orientation in a geotechnical centrifuge

Abstract

Microelectromechanical systems (MEMS) accelerometers are becoming more prevalent in geotechnical engineering and geotechnical centrifuge modelling. In centrifuge experiments these sensors have shown great promise, but still exhibit limitations. This paper proposes a new methodology for the use of single-axis, low-g, high-accuracy MEMS accelerometers to measure the orientation of an object on the vertical rotational plane of centrifugal acceleration and Earth's gravity in a geotechnical centrifuge. The method specifically compensates for the measured cross-axis acceleration by an MEMS accelerometer when in a high-g environment. This is done by determining the apparent internal misalignment of the MEMS sensing unit, relative to its packaging, from a high-g cross-axis calibration. The misalignment can then be used to correct the measured orientation of the sensor relative to a centrifuge gravity vector. When compared to simplified approaches, measurements of absolute orientation are improved by 0·89° and the standard deviation of measurements between multiple sensors is reduced by 0·71°. Overall, this new methodology significantly improves the accuracy of orientation measurements by MEMS accelerometers in the geotechnical centrifuge, opening the door to use these inexpensive sensors in more experiments.