Development of combine grain yield monitor system with self-feedback function

In order to get real time grain yield information, a new kind of grain yield monitor system with error feedback correct function was developed, which was based on the first generation of photoelectric grain yield monitor system. The improved system was consisted of sensor unit, controller unit, display unit and GPS module. The sensor unit included grain volume sensor, elevator speed sensor, grain tank state sensor and unloading grain cylinder speed sensor. The model of grain mass on scraper was established based on optical principle of photoelectric diffuse reflection and grain kinematic principle. Predicted model and diffuse reflectance grain yield monitor software was embedded in the grain yield display terminal. When the elevator scraper of the combine harvester with grain passed diffuse reflectance grain volume sensor, the light path would be blocked intermittently. As a result, the corresponding pulse signal would be generated and meanwhile the elevator rotating speed sensor would output rotating speed signal. According to photoelectric principle, pulse signal was proportional to the thickness of grain on scraper. Subsequently grain yield data acquisition module converted sensor signals into standard signals. Simultaneously, grain yield information including the real-time grain yield, total yield, elevator rotating speed, combine harvester speed, harvest area, longitude and latitude would be obtained and displayed on the terminal. When combine harvester began to unload grain, the self-feedback unit started to work. According to the quantitative spiral conveyor technology, the grain volume was obtained. The unloading grain quality feedback to photoelectric grain yield monitor system calibration obtained the final grain yield. In order to verify the accuracy of the self-feedback unit, static experiment and dynamic field experiment were carried out respectively. The maximum static error was less than 3.90%. Dynamic field experiment was carried out in June, 2017. The experiment results showed that the error was less than 5.80% with self-feedback unit. Both the static experiment and dynamic field experiment indicated that the combine grain yield monitor system with self-feedback function could satisfy the practical need.