This paper presents recent advances made on the Vibrating Integrated Gyro (VIG) developed at ONERA for a few years [1]. Significant improvements in performances have been made possible by several changes in both quartz vibrating structure and electronics architecture. The heart of the VIG is a patented monolithic quartz structure, bringing together the tuning fork resonator and the decoupling frame. The driving mode (in-plane) is classically excited at its resonant frequency, and the Coriolis sensing mode (out of plane) is detected through synchronous demodulation. In the new electronic architecture, the driving mode is excited by Voltage Controlled Oscillator running in a Phase Locked Loop on a high multiple of the target frequency, and acts as an input clock of a digital sequencer made of address counters and programmable memories. The sine signal applied to excitation electrodes is shaped by a digital to analog converter. This makes no difference for the vibrating structure, but the digital sequencer now allows to set accurate phase angles for amplitude sampling and phase locking of the driving mode, as well as phase of demodulation. This discards analog phase shift circuitry on previous architectures, which was sensitive to temperature variations. Besides, amplitude of driving mode and sensor output are realised by differential synchronous sampling, minimizing biases and scale factor errors. Differential operation on both excitation and detection also allows to get rid of capacitive coupling, by implementation of resonator parallel capacitance mirrors close to the quartz structure, with optimal thermal matching. The same process of opposite re-injection is used to cancel quadrature error.
展开▼
