Automatic calibration and nonlinearity optimization for scale factor of micro-electromechanical system gyroscopes under force rebalanced operation

• Published in: Journal of micromechanics and microengineering 2024-10, Vol.34 (10), p.105013
• Main Authors: Shen, Yaojie, Zheng, Xudong, Tong, Wenyuan, Fang, Chen, Jin, Zhonghe, Ma, Zhipeng
• Format: Article
• Language: English
• Subjects: force misalignment angle; force-to-rebalance; micro-electromechanical system gyroscope; scale factor calibration; stiffness modulation
• ISSN: 0960-1317; 1361-6439
• DOI: 10.1088/1361-6439/ad7a09

This paper focuses on automatic temperature sensitivity calibration and nonlinearity optimization of the scale factor (SF) for micro-electromechanical system gyroscopes under force rebalanced operation. The calibration of the SF temperature sensitivity is done based on stiffness modulation by injecting a cosine calibration signal to modulate the resonance frequency of the gyroscope drive mode. The parameters affecting the gyroscope SF are reciprocally proportional to the loop gain of the demodulated calibration signal, enabling a calibrated temperature insensitive SF. Implementing this real-time SF calibration algorithm in an field-programmable gate array (FPGA) platform results in a decreased SF error from 42 416 ppm to 12 141 ppm over a temperature range of 0 °C–50 °C, which is further reduced to 3526 ppm by calibrating the temperature coefficient of the gain ratio of drive and sense mode front-end excitation circuits with the experiment. Additionally, we reveal that the force misalignment angle is a major error source of SF nonlinearity, which is verified experimentally with the result that the SF residual error within the range of 0.1 deg s −1 –200 deg s −1 decreases from 8550 ppm to 3963 ppm by force misalignment angle compensation with force rotation matrices. Due to the elimination of parameters affecting both the SF calibration loop and the real angular readout loop and further calibration of the gain ratio temperature sensitivity of discrete boards, the SF error over temperature is reduced by 12 times, while the maximum SF residual error is optimized by two times as a result of the force misalignment angle compensation.