A Mini- grain Yield Sensor Compensating for the Drift of its Own Output

A very small (0.021 kg) grain yield sensor, comprising an octagonal ring load cell and an impact plate was developed for easily mounting onto grain combines used in East Asian countries. During the interval when the sensor is receiving no impact from the grain, the signals are averaged to determine the instantaneous zero-point; thus the sensor compensates for its own long-term drift. The sensor was mounted on a two-row jidatsu combine, and the weight of grain in the grain tank was estimated in the field experiment. The relative error in the validation without compensation was 19%, whereas that with the compensation decreased to 1.5%. The recommendable range of the threshold for detecting the impact was 0.5 to 4 times the root-mean squared average of the output without throughput of grain.