中文摘要：

拖拉机运输机组总体参数的设计目标多元,约束条件复杂,传统经验法和单目标优化法难以使机组综合性能达到最优。该文以机组动力性、牵引点受力情况、附着性能和经济性最优为目标设计了目标函数;通过分析拖拉机运输机组动力学模型,确定了优化参数;通过研究拖拉机运输机组使用性能,制定了约束模型;采用改进型非支配排序遗传算法,导出了拖拉机运输机组总体参数多目标优化算法。以东方红150拖拉机运输机组为实例,优化了原有拖拉机和挂车的重力参数、质心位置和变速器传动比。设计试验与已有单目标优化方案和原始机组对比,结果为：运输Ⅰ挡和运输Ⅱ挡下,最大爬坡度分别提高1.35%、1.68%和1.38%、0.57%;牵引点受力分别减少1 222、703和2 792、2 125 N;驱动轮最大滑转率更接近特征滑转率;燃油消耗量分别下降12.9%和15.8%;改善了机组动力性、牵引点受力、附着性能、经济性,可为拖拉机运输机组配重方案和总体参数设计提供参考。

英文摘要：

Due to that the design aims for structural parameters of semi-trailer tractor are multivariate and the constricted boundary condition of this designing process is complicated, the utilizations of empirical approach and the single objective optimization can＇ t always promote the comprehensive performance of semi-trailer tractor. Based on non-dominated sorting genetic algorithm Ⅱ （NSGA-Ⅱ）, a new optimizing method about semi-trailer tractor＇s structure parameters was put forward. By analyzing structural and dynamic characteristics of semi-trailer tractor＇s 2-DoF （degree of freedom） model, optimizing principles were established. According to the tractor operation performance including the manipulative stability, negative weight addition, limitation of driving wheel＇s load, load rate of engine power and adhesive characteristic, the constricted boundary conditions were designed. The optimizing objective functions were formulated, which included fuel economy, power performance and force status of tractive point. YTO-150 tractor and the matched semi-trailer were collected as the investigative and optimized object. According to the theoretical analysis and mathematical modeling of the tractor and trailer dynamic performance, the 4 objective functions were divided into 2 groups which involved contradictory relation. After the multiple mathematic conversions of objective functions and constraint functions, the complicated and coupled relationship between the optimal objects could be simplified. Using NSGA-Ⅱ two times, the semi-trailer tractor＇s structure parameters and the gear ratios of transportation work condition were calculated. And relevant program was redacted. Parameters including the gravity of the tractor and semi-trailer, and the position of each part＇s barycenter were optimized. And the transmission ratio of each transportation gear was modified. The figure describing the Pareto front end of each aimed function was plotted. As compared with the primitive semi-trailer tractor, the total