This study investigated the rollover phenomenon of a self-propelled combine harvester during short-distance cross-region travel on a road. The mathematical model of the unsteady lateral multi-degree-of-freedom (multi-DOF) motion of the combine harvester was established with consideration to rear wheel steering, front wheel braking, wheel sideslip, and tyre lateral deflection. By carrying out complex kinematics analysis for the entire vehicle and rotational dynamics analysis for the wheels, the mathematical relationships among the lateral deflection angles of the tyres, the kinematic parameters of the combine harvester centroid, the steering angles of the rear wheels, and the speed components of the wheel centroids along their longitudinal directions were derived and used to transform the established mathematical model into a novel form that considers the steering angles and kinematic parameters as unknown quantities. The lateral load transfer ratio (LTR) model of the combine harvester was established to assess the harvester's rollover critical state. Finally, by considering the steering angles of the rear wheels and the braking torque of the front wheels as model inputs, the rollover mechanism and effects of the structural geometry, steering angles, and braking torque on the LTR of the combine harvester were revealed through numerical calculation, and the safety intervals of the parameters were obtained. The results obtained by this study can provide theoretical and technical support for the dynamic design, control, and rollover protection of combine harvesters.

本研究调查了自行式联合收割机在公路上短距离跨区域行驶时的侧翻现象。综合考虑后轮转向、前轮制动、车轮侧滑、轮胎侧偏，建立联合收割机横向多自由度(multi-DOF)非定常运动数学模型。通过对整车进行复杂的运动学分析和车轮的旋转动力学分析，得到轮胎侧偏角、联合收割机质心运动学参数、后轮转向角之间的数学关系，推导了车轮质心沿其纵向的速度分量，并将其用于将建立的数学模型转换为将转向角和运动学参数视为未知量的新形式。建立联合收割机横向载荷传递比（LTR）模型，评估收割机侧翻临界状态。最后，以后轮转向角和前轮制动力矩为模型输入，通过数值模拟揭示了联合收割机结构几何、转向角和制动力矩对LTR的侧翻机理和影响。计算，得到参数的安全区间。