基于 V／F转换器 AD7742的加速度计信号采集电路设计

摘要

Strap-down Inertial Navigation System ( SINS ) accelerometer output signal requires high-precision acquisition,and the V/F converter circuit has some advantages in accelerometer signal acquisition . A brief introduction is given to the use of the EDK of FPGA in kernel design .Since the output of accelerometer is analog current signal,using ADC for acquisition and conversion is susceptible to temperature drift and reference voltage fluctuations .The I/F circuit acquisition technology has high accuracy,but is difficult to control .On this occasion,using V/F circuit for acquisition of the accelerometers has a great advantage .This paper describes the V/F circuit hardware design process,including the use of the V/F converter AD7742,and the precise instrument amplifier INA 118 .FPGA is used to verify signal acquisition process .Experiment proved the correctness of the design .%　　针对捷联惯导系统对加速度计输出信号需要高精度采集的特点，介绍了采用V/F转换电路对加速度计信号进行采集的优势，并简单介绍了利用FPGA的EDK技术设计内核的过程。由于加速度计输出为模拟电流信号，利用ADC进行采集转换过程容易受温度漂移、参考电压的波动等影响；而I/F电路采集技术虽然精度高但却很难掌握。在这种情况下选用V/F电路对加速度计进行采集处理具有很大优势。介绍了V/F电路硬件设计过程，包括利用V/F转换器AD7742、精密仪表放大器INA118等元器件的使用描述，并利用FPGA对输出频率信号进行采集验证，最后通过试验验证设计的正确性。