A Novel Dynamic Compensated Interface for Lumber Moisture Content Sensor
Jun Cao, Jiawei Zhang, Peng Li · 2006
A novel dynamic compensated interface for lumber moisture content sensors (LMCS) is presented. High precision feedback resistance net is employed which can rapidly develop the measuring precision. Four ordered precise reference resistors with low temperature drift coefficient are employed as intermediate transfers. Combined with this compensation method, microcontroller is embedded in the interface. Programs are compiled to realize automatic calibration and zero adjustment. Without measuring environmental parameters and pre-calibrating, all multiplicative and additive errors of the interface are also eliminated by using this dynamic compensation technique. In the microcontroller, the final result is calculated based on the measurement algorithm. The experimental results show the reliability of the interface is excellent and the accuracy is high even when affected by environment parameters. The relative errors between standard and compensated resistance range from -0.168 % to 0.05 %. When a fluctuant supply voltage plusmn1V as interference is applied, the measurement error is within plusmn0.25%. The MC measuring error is within plusmn0.8% at the final MC (14%~9%) in drying kiln. The performance agrees with the industry requirement