Navigation grade accelerometer with quartz vibrating beam

Abstract

iXBlue is recognized worldwide for its technological expertise in fiber-optic gyroscopes (FOG), demonstrated by the quality and reliability of its inertial systems, from QUADRANS to MARINS [1][2][3]. In order to guarantee independence and increase the performance of accelerometers integrated into its products, six years ago iXBlue decided to develop and industrialize new accelerometer technology at its facility in Lannion, Brittany. This adventure started by technology transfer of the VIA "Vibrating Inertial Accelerometer"[4I[5][6] technology based on MEMS vibrating quartz beams from ONERA (National Office of Aerospace Studies and Research) To transform a laboratory demonstrator into an industrial product named iXAL and meet criteria of quality, reliability, manufacturability and cost effectiveness was a real challenge. The paper looks back on two key elements of the production line: chemical etching of active quartz cells for which innovative solutions have enabled ensure "smooth" surface finishes and characterization method of long term stability by aging (i.e. vacuum stability in the MEMS packaging) The product is now qualified over a wide temperature range (-40 to +80°C). This paper presents results in benign and severe environments (temperature, shock, vibration), better than most accelerometers available on the market. Tests over a reduced temperature range (10 to 60 °C) allow us now to consider using the same accelerometers over reduced temperature range in systems which require a bias repeatability better than 30μg. With these results, this paper demonstrates the usefulness of this technology, based on Quartz MEMS, for the Navigation Grade but also for the Strategic Grade (few μg), not accessible today with Silicon MEMS technology. It is in this way that iXBlue continues the research.