【作者】 李靖；

【导师】 苗明；

【作者基本信息】 大连理工大学 ， 微机电工程， 2012， 硕士

【摘要】 自行式高空作业平台是一种运用工作平台通过伸展机构运送工作人员、工具、设备和材料等到指定位置进行工作的特种车辆。自行式高空作业平台的最快时速为6.8km/h,速度低,当工作地点距离较远时,驾驶自行式高空作业平台到达目的地耗时较长,而且禁止在公路上行驶,此时需要借助卡车或运输车,而运输车的运输平台的宽度有限,为了方便自行式高空作业平台的运输,应减少整机宽度。因此在自行式高空作业平台的底盘处增加轮轴伸缩技术(即扩桥技术),该技术能够改变底盘轮距,使得高空作业平台的底盘存在两种轮距状态。当处于运输状态时,使用较窄轮距；当处于工作状态时,使用较宽轮距。由于存在两种轮距状态,导致存在两个转向机构,而每个转向转向机构均存在转向误差,如何同时减少两个转向误差是本文研究的重点。具体内容如下：(1)描述了轮轴伸缩转向机构在自行式高空作业平台底盘中的应用,建立了轮轴伸缩的转向机构转向误差的数学模型,提出双转向误差的概念。(2)针对带轮距伸缩转向机构的双转向误差问题,建立双转向误差的多目标数学模型,以消除轮胎侧滑为目的,选取相对误差平方的均值为目标函数,以转向机构的底角和腰长为设计变量,建立边界约束条件和性能约束条件,利用多目标遗传算法,借助于MATLAB遗传算法工具箱,解决本文的多目标优化的问题。对于多目标优化后的Pareto解集,本文利用基于变异系数法的解集评价方法,根据决策者的喜好从解集中选出感兴趣的解。以某型号自行式高空作业平台为算例,以多目标优化技术对其进行优化改进,证明了优化方法的可行性和合理性。(3)运用灰色关联度理论,探讨了结构变量对轮轴伸缩转向机构转向误差的敏感度,找到与转向误差关系密切的结构变量,为后文经验公式选择设计变量提供了参考意见。(4)利用优化评价后的解,探索轮轴伸缩转向机构的最优布置规律。布置的原则是消除轮胎侧滑,通过优化技术探索底角和腰长与主销距离之间的规律关系。运用最小二乘法数据处理技术,处理评价的优化数据,得到经验公式,为将来设计同类型自行式高空作业平台的转向机构提供了参考依据。更多还原

【Abstract】 Self-propelled aerial work platform which is called Self-AWP is a special vehicle, intended to move persons to working positions by extending structure. The fastest speed of the Self-AWP is6.8km/h which is very slow. When the working place is farther, it takes much time to drive the Self-AWP to the destination, and it is banned to drive on the road. So the truck or trailer is need, but the width of the truck or trailer is limited. In order to transport the Self-AWP expediently, the width of the Self-AWP should be as short as possible. So the wheel expansion technology or extendable axle technique which is able to change the width is used in the chassis. There are two states of the tread. One is a narrow width when the Self-AWP is in transportation condition. The other is a wider width when the Self-AWP is in working condition. As there are two states of the tread, there are two steering mechanisms and steering errors. How to reduce the two steering errors at the same time is researched in the paper.Firstly, the use of the steering mechanism with extendable axle in Self-AWP is described. Then the model of the steering error of the steering mechanism with extendable axle is established. And the concept of double-error is established at the same time.Secondly, according to the double-error of steering mechanism, the model of the double-error is established as a multi-objective problem. In order to eliminate the sideslip of the tyre, the mean relative error square is consider as the objective function, and the base angle and the waist length are consider as the design variables. Then the boundary constraint condition and the performance constraint condition are established. With the MATLAB genetic algorithm toolbox, the multi-objective problem is solved using multi-objective genetic algorithm. The result of the multi-objective optimize problem is a set of Pareto. Based on pseudo-weighted vector method, the interested set is selected form the set of Pareto. And with a certain type of self-propelled aerial work platform as an example, it is improved by the multi-objective optimize technology and proves the feasibility and rationality of the optimization method.Thirdly, by the grey relational theory, the sensitivity between the structure of variable and steering error is discussed. And the relation between steering error and structure variables is find out, giving opinions for selection of design variables of the experience formula.Last, using the solution after the optimization evaluation, the optimal layout rules of steering mechanism with extendable axle are explored. And the base angle and the waist length are the most important two parameters for steering mechanism. The least square method is used for data processing technology, dealing with the optimization data after evaluation. Then the experience formulas having the two of treads are got, which will guide the future design the same type of steering mechanism with extendable axle in Self-AWP.更多还原