高Q值微机电陀螺的快速起振控制

针对高Q值微机电陀螺的快速起振问题,研究其驱动轴控制方法。分析了高Q值谐振器的振动相位随频率的变化率,阐明了锁相环方案启动时间长且对初始频率偏差敏感的原因。用平均法推导了自激振荡方案下起振初始阶段振幅随时间的变化规律。提出了"自激-锁相"驱动轴控制方案,先采用自激振荡方式使陀螺快速起振,再转为锁相环方式使振动频率精确稳定。经实验测试,采用锁相环方案,当初始频率偏差在±10 Hz以内,陀螺的启动时间为2s;采用自激-锁相方案,只要初始频率偏差在±1 000Hz以内,陀螺均可在0.3s内达到频率误差小于0.01%,在0.4s内达到振幅误差小于0.1%。"自激-锁相"方案大幅度缩短了陀螺的启动时间,而且对陀螺初始频率的设置偏差不敏感,对环境温度变化的适应性好,适用于微机电陀螺的批量生产。

Rapid start-up control of high Q-factor MEMS gyroscope

The control method of the drive axis was investigated with the goal of rapid startup of the MEMS gyroscope with a high Q-factor. The change rate of the vibration phase of the high Q-factor resonator with frequency was analyzed, and the reason for the long starting time of the phase-locked loop scheme in addition to its sensitivity to the initial frequency deviation was elucidated. The variation rule of the amplitude at the initial stage of the self-excited oscillation scheme with time was deduced by using the averaging method. A control scheme that combines the self-exited oscillation loop and the phase-locked loop (SEOL-PLL) of the drive axis was proposed. The self-excited oscillation mode was used to quickly start the gyroscope, and then the phase-locked loop was used to maintain the accuracy and stability of the vibration frequency. In the experiment, when the initial frequency deviation of the PLL is less than ±10 Hz, the starting time of the gyroscope is 2 s. Whereas with the SEOL-PLL scheme, a frequency error of 0.01% is achieved in 0.3 s and an amplitude error of 0.1% is achieved in 0.4 s, as long as the initial frequency deviation is within ±1 000 Hz. The "SEOL-PLL" solution considerably reduces the start-up time and is insensitive to the initial frequency deviation of the gyroscope. It is therefore suitable for the mass production of MEMS gyroscope and has a good adaptability to ambient temperature change.