Electro-hydraulic control of concave clearance in combine harvesters based on kinematic analysis

Adjusting the concave clearance in a threshing-and-separating unit of a combine harvester directly impacts threshing quality and grain loss. This study aims to develop an analytical relationship between the actuator stroke of the electro-hydraulic drive and the clearance size, enabling the implementation of active control algorithms. The research focuses on the tangential-type TSU of the ACROS530 combine harvester. The methodology is based on a kinematic analysis of the concave suspension mechanism, utilizing geometric modeling of the links and determining joint coordinates via the intersection of circles. Based on the resulting model, the authors established the relationship between the clearance and the hydraulic cylinder stroke to formulate the inverse function required for control systems. To minimize computational load, a cubic spline approximation was performed, ensuring high precision within the operational regulation range. The proposed adaptive electro-hydraulic drive scheme incorporates closed-loop control for position, speed, and pressure. The proposed architecture is characterized by reduced energy consumption during load holding and the ability to adapt to varying operating conditions. The study results can be applied to the design and modernization of regulation systems for the threshing and separating units of modern combine harvesters

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