基于正交锁相放大器的微弱应变信号检测系统

摘要

在工业现场利用应变传感器进行形变测量时,被测物在小负荷作用下使得传感器输出的应变信号十分微弱.微弱信号有时甚至会被现场的强噪声信号完全淹没,这时提取有效的微弱信号将变得非常困难.针对这种实际问题,应用相关检测法设计了基于正交锁相放大器的微弱应变信号检测系统.在设计中,待测微弱应变信号通过信号调理、低噪声放大和带通滤波后与严格正交的两路参考信号进行相乘.然后,将乘法器输出信号进行低通滤波得到与待测信号幅值成正比的直流信号.对直流信号经过A/D采集和计算实现微弱应变信号的检测.经过Simulink仿真、现场实验与运行,结果表明系统能有效地抑制噪声信号,准确测量出微弱的应变信号.%When using strain sensor for deformation measurement in industrial field, object tested in a small load makes the sensor output strain signal very weak.And the weak signal can be submerged by the strong noise signal then extracting the effective weak signal can become very difficult.Aiming at this practical problem, the weak strain signal detection system based on the quadrature phase lock amplifier was designed by using the correlation detection method.In the design, the tested weak strain signal after signal conditioning, lowing noise amplifier and band pass filter was multiplied by the strictly orthogonal two reference signals.And then through the low pass filter, the DC signal proportional to the amplitude of the measured signal was obtained.Finally, the system achieved the detection of weak strain signal through the A/D acquisition and calculation.Through the Simulink simulation, field experiment and operation, it shows that the system effectively inhibits the noise signal, accurately measures the weak strain signal.