事故再现复合形优化算法及其应用

A Complex Optimization Algorithm for Accident Reconstruction and Its Application

为了适应交通事故鉴定与分析工程实践中对基于计算机事故仿真的事故再现人工调整优化方法论的需求,提出了一种新的事故再现优化算法。首先,在对交通事故再现优化问题进行数学描述的基础上,提出了基于隐式仿真的事故再现优化问题的特征,包括:很难对事故仿真模型进行求导、事故仿真"正向迭代"流程与事故再现"反向推导"的要求之间存在矛盾、事故再现对优化效率有较高的要求;其次,阐述了复合形法的基本原理,提出了复合形优化算法的迭代步骤和流程,其基本方式是通过构建简单几何图形(n维空间中具有n+1个以上的顶点组合而成的多面体)并比较各顶点的目标函数值,以目标函数值较小的顶点取代目标函数值最大的顶点,以此反复迭代直至满足收敛指标后得出最优解;最后,基于一起发生在四川成都某快速路上的车辆碰撞行人事故案例,结合多刚体碰撞建模系统PC-Crash软件进行事故仿真建模,利用复合形算法经6步迭代实现车辆碰撞速度和附着系数修正值两个参数的优化求解,并用事故现场监控视频解析数据进行了验证。研究表明:复合形优化算法构思较为直观、收敛较快,不需要对事故仿真模型进行求导,对事故类型也没有限制,适用于优化变量较少的、基于计算机事故仿真的事故再现人工调整优化。

In order to fit with the needs of methodology of manual optimization in computer simulation-based accident reconstruction in the actual application of traffic accident analysis,a new optimization algorithm for accident reconstruction is proposed. First, based on the mathematical description of traffic accident reconstruction optimization, the characteristics of implicit simulation-based accident reconstruction optimization are put forward,including: it is difficult to take the derivative of accident simulation model,there is the contradiction between the "backward derivation"requirement of accident reconstruction and the"forward iterative"process of accident simulation,accident reconstruction has a high requirement for the efficiency of optimization. Second,the basic principle of complex method is elaborated,and the iterative steps and the process of the algorithm are also developed. The basic means of complex method is to construct simple geometry( a polyhedron with more than n + 1 vertexes in n-dimensional space) and compare the values of objective function at every vertex,and then the vertex with the largest value will be replaced by thevertex with smaller value,the final optimal solution will be obtained by repeated iterating until satisfying the convergence conditions. Third,a real-world vehicle-pedestrian accident on an expressway in Chengdu,Sichuan,is selected to be simulated and modeled based on PC-Crash software which is a multi-body system for impact modeling,the newly-developed complex algorithm is applied to conduct the optimization,the final optimal solution of vehicle impact speed and corrected adhesion coefficient are obtained via 6 iterations,and the result is also verified by data of surveillance video which captured from the accident. It shows that complex algorithm has intuitive conception with fast convergence,it has no need to take the derivative of accident simulation model,it also has no restriction of accident types,and it is applicable for manual optimization of computer simulation-based accident reconstruction which has less number of optimization variables.