Mathematical model for bale-density prediction in large steel roller-type round balers during bale rolling

[Display omitted] •A mathematical model for the real-time prediction of bale density was constructed.•A method for the dynamic measurement of bale density was proposed.•Bale density based on the radial reaction forces of steel rollers was characterized.•The accuracy of bale density was high up to 93%–97% by the data acquisition system. To realize the intelligent production of straw bales and improve their economy, the density of straw bales in the working process of large-scale steel roller-type round balers must be measured in real time. Therefore, this study analyzes the forces acting on steel rollers and bales in the bale rolling process, constructs a mathematical model to predict the density of molded bales, and proposes a method for dynamically measuring the density of bales in a round bale machine. Sunflower straw was selected as the test material, and a bale density model validation test was conducted at a test stand. The results showed that the accuracy of the measured bale density of the data acquisition system ranged from 93% to 97%, verifying that the mathematical model for bale density prediction had good accuracy. This study provided an effective strategy for round baler design.