The VIA vibrating beam accelerometer: a new quartz micromachined sensor

ONERA, the French National Establishment for Aerospace Research, under the financial support of the DGA (The French MoD Procurement Agency), has been developing a micro-machined quartz vibrating beam accelerometer called VIA (Vibrating Inertial Accelerometer). This sensor exploits the frequency change of a quartz resonator when submitted to an acceleration. The main targeted applications are the guidance and the attitude control of tactical missiles, as well as the inertial navigation of aircraft, helicopters and ground vehicles (coupled with radio-electric positioning systems such as the GPS receiver). The VIA concept has been selected to meet these objectives. First, the monolithic configuration of the transducers is well suited to chemical etching process and miniaturization. Secondly, the choice of vibrating beams as sensitive elements, combined with excellent quartz mechanical properties, gives a very good stability of the scale factor. Third, the performed optimisation of the transducer leads to a very good insulation of the active part with respect to the mounting areas of the transducer, suitable to bias stability. In order to reduce the thermal sensitivity, the accelerometer is composed of two transducers operating in differential mode.