Micro angular rate sensor design and nonlinear dynamics

We present an innovative micro gyroscope that is capable of detecting three-dimensional (3-D) angular motions. The motion of each sensing element is, by mechanical design, restricted to move in a direction orthogonal to each other such that measurements by high-resolution capacitors with signal processing circuits are decoupled and precisely represent, to some extent, angular velocity components in three axes. In order to ensure better repeatability and more reliability, the suspension flexures and stiffness are studied such that the stress of the proposed micro gyroscope is reduced, but the stroke of angular displacements is increased. Owing to the complicated geometry of the suspension flexures, the finite element method (FEM) is employed to obtain more exact stiffness value and compared with theoretical analysis. The dynamic model of the proposed gyroscope is established to include nonlinear terms and gyroscopic effects. The entire micro device can be produced merely by surface micromachining and wet etching such that the mass production cost has been considered at the design stage but the resolution, bandwidth, and decoupling capability of tri-axis detection are expected to be enhanced.