Grain flow rate sensing for a 55 kW full-feed type multi-purpose combine

Real time sensing of crop yield is critical for a successful implementation of precision agriculture.Yield monitoring system is an optional component of a 55 kW multi-purpose combine harvester,developed in Korea,for both domestic and global markets,especially Asian countries where field sizes are relatively small.The aim of the present study was to fabricate and evaluate the performance of a grain flow sensor suitable to the mid-sized full-feed type combine for rice,soybean,and barley.Firstly,commercially available non-contact type sensing modules(optical,ultrasonic,laser,and microwave modules)were chosen for alternative candidates,to be further tested in a laboratory bench.Through the laboratory tests,the ultrasonic module was selected as a potential approach and the performance was improved by increasing the number of modules and their layout.Finally,the improved grain flow sensor was evaluated during field harvesting operation.Field tests with the improved grain flow sensor showed a good potential for rice(R^(2)=0.85,RMSE=126.14 g/s),soybean(R^(2)=0.78,RMSE=43.87 g/s),and barley(R^(2)=0.83,RMSE=37.39 g/s).Further research would be necessary for improvement and commercialization,through various signal processing and field tests under different field and crop conditions.