Monitoring method and test of wheat harvester loss rate based on PVDF sensor

Abstract

Aiming at the problem that the cleaning loss of wheat harvester affects the harvesting quality, we developed a loss detection system based on PVDF (polyvinylidene fluoride) piezoelectric film cleaning loss sensor. After the study of the relationship between the impact speed and the piezoelectric effect of the scavenging screen, the filtering method for discriminating the grain signal is found. The effect of fan speed on grain quality distribution behind the clearance screen of longitudinal axial flow wheat harvester was studied. The results showed that the effect of fan speed 1100∼1200r/min on grain quality distribution was not obvious. The optimum monitoring area of the sensor was found by studying the distribution law of grain quality of the clear separation loss, and the mathematical model of the monitoring of the cleaning loss was established. The result of the model test showed that the deviation of the model was less than 1.169, and the accuracy of the model was higher. This paper presents a method for calculating the cleaning loss rate based on the feed rate of the combined harvester. The influence of the feed rate on the monitoring accuracy of the cleaning loss rate was studied by bench test. The relative error of the monitoring results is between 1.84% and 3.15%, which indicates that the combined harvester cleaning loss monitoring system developed in this paper has a high monitoring accuracy.