Research on the Sensitive Mechanism of Open Z axis Fluidic Gyroscope based on MEMS

In this paper, we reported the sensitive mechanism of a Z axis fluidic gyroscope based on open airflow channel. The 3D transient finite element analysis method based on fluid-structure interaction was used to calculate the airflow field inside of the sensitive element. Calculation and results indicated that: (1) When at the static state, sensitive jet flow distributed symmetrically according to hotwires r(1) and r(2), the two arms of Wheatstone Bridge, the velocity gradient between which is zero. Therefore, the bridge is balanced and output voltage is zero. When angular velocity is applied, sensitive jet flow deflected along Z axis because of the Coriolis Force, sensitive jet flow distributed dissymmetrically according to r(1) and r(2), thus the velocity gradient beta(X) between r(1) and r(2) increased with the increasing angular velocity. Additional, at the same condition of other materials and result parameters, the resistance value of two hotwires changed dissymmetrically because of the dissymmetric heat exchange between r(1) and r(2) with sensitive jet flow. Therefore, the bridge is not balanced anymore and outputs an unbalanced voltage proportional to applied angular velocity. (3) In the input range of +/- 120 degrees/s, sensitivity of gyroscope is SFZ=2.0 mu V/degrees/s, and simultaneously, the nonlinearity is better than 0.5% In addition, the power consumption is 5.2mW, the resistance value R of hotwire is 3 Omega and the temperature coefficient of resistance of hotwire is 2600ppm/degrees C.There is a directional flow between two inlets and outlet inside of the sensitive element of this open Z axis gyroscope based on MEMS, without an circulation airflow. The structure of sensitive element can be briefness.