Geometry-Based Measurement and Error Compensated for Cotton Bale Dimensions in Packing Cotton Pickers

Precision agriculture is a key trend in future agricultural development. Nevertheless, as a key crop in the global economy, cotton precision harvesting remains in its infancy. Therefore, this study proposes a method to precisely regulate cotton bale dimensions in packing cotton pickers, aiming to advance the precision harvesting of cotton. Firstly, based on the two basic assumptions, the relationship between the rotation angle of the rocker-arm component and the cotton bale dimension was derived. In addition, the one-to-one correspondence between the rotation angle and the dimension was demonstrated. Subsequently, a numerical case study was conducted to validate the method’s feasibility initially. However, solver failure occurred at larger angles, necessitating model refinement by incorporating the elastic deformation of the packing belt. Finally, a prototype was built and field tests were carried out. Based on the first field experiment results, the error caused by model simplification was compensated with quadratic polynomial least squares fitting. After compensating, the second field experiment results show that the absolute error in bale dimension remained below 49 mm and the relative error below 2.13%, as the diameter of the cotton bale was less than 2300 mm. This study lays a superior foundation for the precision harvesting of cotton.