基于算法融合的全量程高精度激光CH_(4)传感器

Full Range and High Precision Laser CH_(4) Sensor Based on Algorithm Fusion

为实现对CH_(4)气体的全量程、高精度测量,研发了一种基于可调谐半导体激光吸收光谱(TDLAS)技术、融合波长调制光谱一次谐波归一化二次谐波(WMS-2f/1f)技术和直接吸收光谱(DAS)技术的全量程激光CH_(4)传感器。该传感器采用中心波长为1653.72 nm的分布式反馈激光器作为探测光源,通过微控制单元主控芯片实现对CH_(4)体积分数的实时反演,提出一种基于模糊控制S型隶属度函数的波长调制光谱和直接吸收光谱的气体体积分数反演数据融合算法。通过对10台传感器进行最小均方根误差(RMSE)实验测试,确定了最优模糊区间为0.024~0.038。经比较,该算法相较于传统全量程测量方法有效减小了系统的均方根误差。研究结果表明,传感器全量程测试的相对误差范围为-5.28%~3.67%,表明其对于全量程测量具有较高的精度。利用3×10^(-4)2f/1f测量信号评估得到传感器检测下限为3.04×10^(-5),结合长度为0.07 m的光程,1 m光程内最低可检测的积分气体体积分数为2.13×10^(-6)。对体积分数为0.01的气体长时间测量并统计其反演体积分数的高斯分布,统计最大值范围为0.997×10^(-2)~1.002×10^(-2),高斯拟合曲线半峰半宽为1.43×10^(-4)。

To achieve full range and high-precision measurement of CH_(4) gas,a laser CH_(4) sensor based on tunable diode laser absorption spectroscopy(TDLAS)technology has been developed,which integrates wavelength modulation spectroscopy first harmonic normalization second harmonic(WMS-2f/1f)technology and direct absorption spectroscopy(DAS)technology.The sensor utilizes a distributed feedback laser with a central wavelength of 1653.72 nm as the detection light source,and realizes realtime inversion of CH_(4) volume fraction through a built-in microcontroller unit main control chip.A fusion algorithm of WMS and DAS inversion volume fraction data based on fuzzy control S-type membership function is proposed.Minimum root mean square error(RMSE)verification is performed on ten similar sensors,and the optimal fuzzy interval is determined to be in the range of0.024?0.038.Through comparison,this algorithm has effectively reduced the root mean square error of the system compared to the traditional full range measurement method.The test results demonstrate that the remeasurement error range of the full range test of the sensor is-5.28%?3.67%,indicating that the sensor has high accuracy for the full range measurement.The detection limit of the sensor is evaluated at 3.04×10^(-5)using a 3×10^(-4)2f/1f measurement signal,combined with the optical path length of0.07 m,and the minimum detectable integral volume fraction in 1 m optical path is 2.13×10^(-6).The 0.01 volume fraction gas is measured for a long time and the Gaussian distribution of its inversion concentration is calculated.The maximum statistical value is in the range of 0.997×10^(-2)?1.002×10^(-2),and the half width at half maximum of the Gaussian fitting curve is 1.43×10^(-4).