Abstract
This study addresses the challenges of instability and rollover faced by agricultural machinery operating on complex hilly and mountainous terrains by proposing an active leveling system for an articulated unmanned tractor. The proposed system is an independent, vehicle-mounted swing platform that levels the equipment-carrying surface rather than the entire tractor body, facilitating modular retrofitting and enhancing operational safety on complex terrains. The system utilizes a hydraulic parallel-swing platform structure, equipped with a dual-axis tilt sensor to monitor the tractor’s body tilt in real-time. In combination with a hydraulic drive system, the platform adjusts the tractor’s posture to ensure stable operation on slopes of up to 30°. The system’s performance is evaluated through degrees of freedom analysis, inverse kinematic solution, dexterity analysis, and workspace evaluation. A multibody dynamics model is developed, and kinematic simulations are performed to verify its leveling capabilities. Co-simulations using Simulink and RecurDyn are employed to study the system’s response and stability under complex terrain conditions, as well as the leveling accuracy of the pitch and roll angles. Finally, bench and field tests were conducted, demonstrating that leveling errors peak at extreme angles, with a maximum roll error of 1.17° and a maximum pitch error of 0.87°, meeting the precision requirements for angle control on uneven terrain.
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