Model-Based Digital Implementation of Automotive Grade Gyro for High Stability

Abstract

SensoNor has together with Imego for the last three years developed and tested gyro concepts with bias-stability in the range of a few deg/h using SensoNor’s existing roll-over vibratory gyro die. This has been possible by improving the LNA’s and implementing a modelbased concept where the feedback loops are implemented in the digital domain. The digital part includes 5th order sigma-delta AD converters and 5th order feedback filters to accommodate for an optimized trade-off between complexity and signal-noise ratio. The approach allows for using a low cost MEMS gyro die measuring 3 by 2.5mm achieving close to navigational performance. The “Allan Variance” method as well as the unquestionable measurement of earth rotation has been performed to prove bias-stability. The novel digital algorithm based approach is a significant leap enabling flexible high performance solutions to be built upon fairly conventional MEMS structures.