微型热对流陀螺仪敏感信号检测

Detection of the Output Signals of Micromachined Gas Inertial Sensor Based on Convection Heat Transfer

针对微型热对流陀螺仪敏感输出信号非常微弱、不易测量的特点,本文提出了一种热对流陀螺仪敏感信号检测方法.采用交变电流来驱动加热器,产生交变的流速.在外界输入角速度时,产生了交变的哥氏加速度,从而引起对称于Y轴两边的气体流速方向发生偏转,使热敏电阻周围的温度发生改变,热敏电阻阻值也随之变化.差动检测电路将热敏电阻阻值变化转换成交变电压.采用基于相关检测的相敏解调方法提取出有用信号,通过低通滤波器、放大器,最终得到直流电压,该电压信号正比于外界输入角速度.实验表明,交流驱动和相关检测的方法能有效地抑制低频噪声干扰、提高检测精度.

The output signals induced by micromachined gas inertial sensor based on the principle of convection heat transfer were too weak to be detected. A now method to detect this kind of output signals is presented. An alternating current is used to heat the central heater and the alternating fluid velocity comes into being. On one side of the Y axis, the alternating Coriolis accelerations, induced by an external angular velocity,will cause the deflections of fluid velocity to cool the gases around the two thermistors in pairs and change the resistances of thermistors, in the other side of the Y axis, the deflection and the changes are opposite. Thus,the difference of resistances will indicate the input of the angular rate of motion. Wheatstone bridge circuit converts the resistance changes to the voltage difference. The method of phase sensitively demodulation （PSD）, based on the correlation detection, is to be used to select out the required signals and then pass them through low-pass filters and amplifiers and at last obtains the DC voltage proportional to the external angular velocity. The response experiments show that the method of alternating drive with correlation detection can restrain the low frequency noises effectively and raise the examination accuracy.