MEMS thermal gyroscope with self-compensation of the linear acceleration effect

摘要

The MEMS (micro-electro-mechanical system) thermal gyroscope uses gas instead of a solid proof mass to detect Coriolis acceleration and provides better high-shock and strong-vibration resistance than the MEMS mechanical gyroscope. Despite its mechanical robustness, the output of the MEMS thermal gyroscope is affected by linear acceleration. The MEMS thermal gyroscope described in this paper includes two symmetric heaters and two symmetric temperature sensors. By alternating power to the two heaters, a bidirectional flow of expanding gas is created. The Coriolis acceleration deflects the symmetric gas flow and produces a differential temperature between the two temperature sensors. By reducing the heaters' switching frequency, we are able to compensate for the linear acceleration effect of the thermal gyroscope. At a low gas flow frequency, the thermal gyroscope operates in both transient and steady states. The differential temperature acquired in the transient state is a combination of the signals produced by acceleration and rotation. However, in the steady state, the velocity of gas flow produced by gas expansion and contraction drops to zero. At this point, the desired Coriolis acceleration diminishes, and the device operates solely as an accelerometer. Thus, the differential temperature signal detected in the steady state can be used to compensate for the differential temperature signal detected in the transient state. This method also provides both rotational and acceleration signals from the same device.