Design and Analysis of a Novel Fully Decoupled Tri-axis Linear Vibratory Gyroscope with Matched Modes.

Dunzhu Xia,Lun Kong,Haiyu Gao

doi:10.3390/s150716929

Abstract

We present in this paper a novel fully decoupled silicon micromachined tri-axis linear vibratory gyroscope. The proposed gyroscope structure is highly symmetrical and can be limited to an area of about 8.5 mm × 8.5 mm. It can differentially detect three axes’ angular velocities at the same time. By elaborately arranging different beams, anchors and sensing frames, the drive and sense modes are fully decoupled from each other. Moreover, the quadrature error correction and frequency tuning functions are taken into consideration in the structure design for all the sense modes. Since there exists an unwanted in-plane rotational mode, theoretical analysis is implemented to eliminate it. To accelerate the mode matching process, the particle swam optimization (PSO) algorithm is adopted and a frequency split of 149 Hz is first achieved by this method. Then, after two steps of manual adjustment of the springs’ dimensions, the frequency gap is further decreased to 3 Hz. With the help of the finite element method (FEM) software ANSYS, the natural frequencies of drive, yaw, and pitch/roll modes are found to be 14,017 Hz, 14,018 Hz and 14,020 Hz, respectively. The cross-axis effect and scale factor of each mode are also simulated. All the simulation results are in good accordance with the theoretical analysis, which means the design is effective and worthy of further investigation on the integration of tri-axis accelerometers on the same single chip to form an inertial measurement unit.

Highlights

Micromachined gyroscopes are an important kind of inertial sensor used to measure the angular rate or attitude angle
To improve the performance of a tri-axis gyroscope, it is essential to avoid the coupling between the drive and sense modes
To improve the performance of the tri-axis gyroscope, the quadrature error correction electrodes, stiffness tuning electrodes and feedback electrodes are taken into consideration in all the sense modes in the structure design

Summary

Introduction

Micromachined gyroscopes are an important kind of inertial sensor used to measure the angular rate or attitude angle. They have been developed rapidly in recent years as widely used miniaturized angular rate sensors. Since they have the merits of small volume, light weight, high reliability, low cost and potential for mass production, micromachined gyroscopes are available for various applications like aerospace measurement, balance control, inertial navigation, and the electronic stability programs, etc. In a tri-axis gyroscope, the lateral-axis sensing needs an out-of-plane movement. Compared with an in-plane z-axis silicon micromachined gyroscope which is available for inertial-grade applications, the lateral-axis gyroscope faces more challenges in achieving good performance.

Methods

Results

Conclusion