基于AD7124的高精度MEMS加速度计信号处理系统

High-precision Micro-electro-mechanical System Accelerometer Signal Processing System Based on AD7124

摘要:

为降低加速度计存在的零点漂移对测量精度的影响,满足低量程微机械(MEMS)加速度计的测量精度和漂移需求,设计了一种基于AD7124的高精度MEMS加速度计信号处理系统。以STM32F303CBT6为核心控制器,驱动高精度模/数(A/D)转换芯片AD7124进行数据采集。设计脉冲宽度调制输出方波作为加速度计的激励信号,运用加权移动平均滤波对信号进行去噪和平滑,提出一种零点漂移抑制与跟踪的算法,解决了零点漂移过大的问题。测试结果表明,加速度计在±1g量程下的灵敏度为146mV/g,经过数字滤波后的加速度计输出稳定度提高了5.97倍,最终零偏稳定性由45.850mg/h改善为0.055mg/h。

Abstract:

To reduce the influence of the zero-drift problem on the measurement accuracy of an accelerometer and satisfy the measurement accuracy and drift requirements of a low-range micro-electro-mechanical system (MEMS) accelerometer, a high-precision MEMS accelerometer signal processing system based on AD7124 is designed. The hardware uses STM32F303CBT6 as the core controller to drive AD7124, and a high-precision analog-to-digital (A/D) conversion chip is used for data acquisition. In the software, the pulse width modulation (PWM) output square wave is designed as the excitation signal of the accelerometer, and the weighted moving average filter is used to denoise and smooth the signal. An algorithm for zero-drift suppression and tracking is proposed, which solves the problem of excessive zero-drift. After testing, the sensitivity of the accelerometer is 146mV/g at the ±1g range, the output stability of the accelerometer after digital filtering is increased by 5.97 times, and the final bias stability is improved from 45.850mg/h to 0.055mg/h.