基于主动光源的手持式作物NDVI传感器设计与试验

Design and Experiment of Handheld Crop NDVI Sensor Based on Active Light Source

摘要:

为满足现代农业对农作物在各生长阶段整体生长状态与发育趋势的检测需求，实现农作物快速、无损的检测目标，研究设计了一种基于主动光源的手持式作物NDVI（归一化植被指数）传感器。该传感器检测终端集成波长650、850nm的窄带LED以及Si PIN光电探测器，确保光源的稳定输出和接收端的精确响应。以4个不同施肥梯度下的60个小麦作物冠层为研究对象，基于信号调制解调的原理，对植物冠层的NDVI值进行测量。研究结果表明，该传感器的光源稳定性良好，2个波段的标准差均控制在0.9mV以内；在不同测量高度下进行的光学标定实验中，测量结果与标定参数之间呈现出显著的线性关系，决定系数（R2）均高于0.97；当测量高度在20～40cm范围内变化时，NDVI的输出结果基本不受测量高度的影响，其均方根误差（RMSE）分别为0.025和0.015。此外，该传感器能够有效降低外界环境光变化的干扰，确保测量结果的稳定性。与参考仪器对比分析结果显示，二者在NDVI测量结果上具有高度一致性，R2达到0.79，RMSE仅为0.031。实验结果充分证明了自主研发的手持式作物长势检测仪在实际应用中具有较高的可靠性和准确性，能够为作物长势监测提供有力的技术支持。

Abstract:

Aiming to address the needs of modern agriculture in monitoring the overall crop growth status and developmental trends across various growth stages, and enable rapid, non-destructive crop assessment, a handheld crop normalized difference vegetation index (NDVI) sensor based on an active light source was developed. The sensor integrated narrow-band LEDs at 650 and 850nm, along with Si PIN photodetectors, ensuring stable light output and precise signal acquisition. NDVI values were measured by using signal modulation and demodulation techniques across 60 wheat canopies subjected to four different fertilization levels. Experimental results demonstrated excellent light source stability, with standard deviations at both wavelengths maintained within 0.9mV. In optical calibration experiments conducted at varying measurement heights, the results exhibited a strong linear relationship to the calibration parameters, with correlation coefficients (R2) exceeding 0.97. When the measurement height ranged from 20cm to 40cm, NDVI outputs remained largely stable, with root mean square errors (RMSE) of 0.025 and 0.015, respectively. Moreover, the sensor effectively mitigated the influence of ambient light fluctuations, ensuring consistent measurement results. A comparative analysis with a reference instrument demonstrated strong agreement in NDVI measurements, with R2 of 0.79 and RMSE of just 0.031. These results confirmed that the developed handheld crop growth sensor delivered high reliability and accuracy in practical applications, providing robust technical support for crop growth monitoring and a sound scientific foundation for modern agricultural production management.