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研究了MEMS陀螺驱动环路的数字∑Δ闭环控制。基于MEMS陀螺机械结构的二阶谐振特性,采用自激振荡的方式实现驱动闭环,通过数字延迟链实现相位控制,通过PI控制器保证驱动模态恒幅振动。设计4阶机电结合带通∑Δ调制器代替数模转换器(DAC)实现静电力反馈,来抑制闭环控制系统的带内噪声,同时降低驱动级模拟电路的复杂度。通过FPGA进行实验验证,测试结果表明应用该驱动环路,其驱动模态振动幅值稳定性为3.67×10~(-4),MEMS陀螺输出零偏不稳定性为1.219°/h。
The digital ΣΔ closed-loop control of MEMS gyroscope drive loop is studied. Based on the second-order resonant characteristic of the MEMS gyroscopic mechanical structure, the self-excited oscillation is adopted to drive the closed loop and the phase control through the digital delay chain. The PI mode controller ensures the constant amplitude vibration of the driving mode. The fourth-order electromechanical band-pass ΣΔ modulator is designed to replace the digital-to-analog converter (DAC) for electrostatic force feedback to suppress the in-band noise of the closed-loop control system and reduce the complexity of the driver stage analog circuit. The experimental results show that the stability of driving mode vibration amplitude is 3.67 × 10 ~ (-4) and the bias instability of MEMS gyroscope is 1.219 ° / h.