基于遗传算法的大型装载机工作装置优化设计

发布时间：2019-04-03 12:20

【摘要】：装载机工作装置优化是比较典型的机构优化问题,而与普通优化问题不同之处在于该优化没有明显的目标函数,或者说目标函数较多,约束条件和目标函数之间没有明显的界限,如可将传力比作为目标函数也可将平移性或自动放平性作为目标函数甚至可以将卸高、卸距当作目标函数。设计变量可以是各铰点的坐标,但是以坐标作为设计变量不利于设计者对机构的直观了解,因此我们将各铰点间的距离和一些必要的角度作为设计变量,那么各铰点的位置就可以通过这些长度变量以及角度表示出来。为验证结果是否可行,选用虚拟样机仿真试验的方法。这种方法可大大降低了试验成本,同时得到的结果具有足够的可信度。确定设计变量和目标函数后,可以根据性能要求建立约束条件,建立约束条件是整个设计过程中的重中之重,因此这里用了大量篇幅详细讲述了约束的建立过程,之后就可以利用先进的计算机算法——遗传算法进行求解,求解时为解决初始种群匮乏的问题,可以将开始优化得到的非最优解添加到初始种群中,逐步使其丰满,再逐步淘汰初始种群中的劣质个体,以得到最优解。本论文针对LW1200K的工作装置初步设计方案,在保证卸载高度和卸载距离的基本前提下,进行了关键铰接点的位置优化分析,完成了铰接点坐标值的初步确定,通过ADAMS进行了关键件的受力状态分析,结果可以满足12吨大型装载机的设计需求。
[Abstract]:The optimization of loader working device is a typical optimization problem of mechanism, and the difference between the optimization problem and the ordinary optimization problem is that the optimization has no obvious objective function, or that there are more objective functions. There is no obvious boundary between the constraint condition and the objective function, for example, the force transfer ratio can be regarded as the objective function, the translation or automatic leveling can be regarded as the objective function, even the unloading height and the unloading distance can be regarded as the objective function. The design variable can be the coordinates of each hinge point, but taking the coordinate as the design variable is not conducive to the designer's intuitive understanding of the mechanism, so we take the distance between the hinge points and some necessary angles as the design variables. Then the position of each hinge can be expressed by these length variables and angles. In order to verify the feasibility of the results, the method of virtual prototype simulation is selected. This method can greatly reduce the cost of the test, and the results obtained are reliable enough. After determining the design variables and objective functions, the constraint conditions can be established according to the performance requirements, which is the most important part of the whole design process. Therefore, the establishment process of the constraints is described in detail in this paper. Then we can use the advanced computer algorithm-genetic algorithm. In order to solve the problem of lack of initial population, we can add the non-optimal solution to the initial population and gradually make it full. In order to get the optimal solution, the inferior individuals in the initial population are phased out step by step. In this paper, according to the preliminary design scheme of LW1200K's working device, under the basic premise of ensuring the unloading height and unloading distance, the position optimization analysis of the key hinge point is carried out, and the initial determination of the coordinate value of the hinge point is completed. The stress state of the key parts is analyzed by ADAMS, and the results can meet the design demand of 12 ton large loader.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH243

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