Real-Time Phase Compensation for Scale Factor Nonlinearity Improvement Over Temperature Variations for MEMS Gyroscope

High-performance MEMS gyroscope puts forward the higher request to the scale factor nonlinearity especially in variable-temperature environment. The scale factor nonlinearity over full temperature range rarely studies. In this paper, we focuses on the scale factor nonlinearity over full temperature range. The variations of the scale factor nonlinearity as the temperature were tested based on the MEMS butterfly gyroscope. The experimental results showed the U-shape curve of the output rate error so that the scale factor nonlinearity got large. The theoretical model of the scale factor was built and the phase error was found to be responsible for the U-shape error curve. Meanwhile, the phase error was identified to be variable over full temperature range experimentally, which meant it was critical to compensate the phase error in real time for improving the scale factor nonlinearity over full temperature range. A novel close-loop phase compensation system was designed by introducing a disturbance signal and experiments showed phase error was compensated in real time. After real-time phase compensation, the U-shape curve of the output rate error was eliminated and the scale factor nonlinearity decreased by about 10 times from 212.5 ppm to 19.5 ppm at the temperature ranged from -40 degrees C to 80 degrees C, which reached an excellent level for the rate MEMS gyroscopes.