Design of a Distance-Compensated Infrared Thermometer for Canopy Temperature Monitoring

Area of Science:

• Precision Agriculture
• Sensor Technology
• Infrared Thermometry

Background:

• Single-pixel infrared (IR) thermometers face distance-dependent errors, limiting their use in precision agriculture.
• Existing solutions for IR thermometry errors are often complex, costly, or require fixed installations.
• Accurate non-contact temperature monitoring is crucial for crop management and yield optimization.

Purpose of the Study:

• To design and develop an IR thermometer system with a lightweight algorithm for distance compensation.
• To enable flexible, height-independent deployment of single-pixel IR thermometry.
• To improve the accuracy and reliability of non-contact temperature measurements in agricultural settings.

Main Methods:

• Integrated IR thermometer with ultrasonic distance sensors.
• Employed a distance-bias lookup table (LUT) calibrated at setpoints.
• Utilized bilinear interpolation for real-time signal conditioning and temperature correction.

Main Results:

• Reduced distance-dependent residual Root Mean Square Error (RMSE) to below 0.20 °C across 5-200 cm.
• Uncompensated errors reached -5 °C at 200 cm, while the compensated system minimized this drift.
• Maintained short-term repeatability with standard deviations between 0.08 °C and 0.12 °C from 20-200 cm.

Conclusions:

• The developed IR thermometry system effectively compensates for distance-dependent errors using signal processing.
• The system supports flexible deployment for applications like canopy temperature monitoring in precision agriculture.
• Preliminary field tests show promise for outdoor applications, though further validation is needed.