摘要
目前,道路交通安全评估主要通过对交通事故进行分析来完成的,该方法无法对未建成的道路进行安全评估,并且用于分析的事故数据的采集有相当难度。本课题的主要研究内容是在分布式交互仿真系统上模拟真实的道路环境和驾驶环境,采集实验数据,通过对实验数据的分析来进行交通安全评估。
本文研究了对原有仿真模拟器的视景系统的改进方案,设计并实现了通过多通道技术将原有的单通道视景系统扩展为多通道视景系统的方法,通过此方法可以增大驾驶员的视野范围提高系统的“沉浸感”,更加真实的模拟实际道路环境下驾驶员对道路环境的感知,提高安全评估的可信度。
本研究需要模拟真实道路环境下车辆间的交互情况,因此需要在多个仿真节点间完成数据交换和采集工作,这对节点间同步的实时性有较高的要求。在本文中所探讨的同步问题主要涉及到两个方面:时钟同步和数据信息同步。其中时钟同步是利用在不同节点间传递具有时间戳的控制信息来实现的,目的是让多个节点具有相同的本地时间,方便对系统的控制和数据采集。数据同步是通过将不同节点间的控制及车辆状态信息在一定的控制策略下进行交换,使每个仿真节点上相应的实体状态一致,在系统进行数据采集时获得一致的实验数据。
为了数据交换和同步的需要,本文设计并实现了基于UDP的可靠传输机制RUDP(reliable UDP)。该机制是在UDP协议的基础上增加应答机制、数据确认及重传、拆/装包机制来实现可靠的信息传送。RUDP结合了UDP协议的高效和TCP协议的可靠性,为基于该协议的同步机制提供支持。
本文通过对系统进行需求分析,提炼出道路交通安全评估所需的主要参数,并设计出满足系统要求的数据采集方法。利用数据库设计技术设计出满足道路交通安全评估的数据库管理系统,将采集到的实验数据保存在数据库系统中,方便在实验结束后对数据进行分析和管理。
At present,the road safety evaluation is carried out by road traffic accident analysis and research,the method can not be used to the uncompleted road and the collection of accident data is a considerable degree of difficulty.The purpose of the research is to build a distributed interactive virtual simulation system on the road environment and driving environment,using data acquisition method to obtain the necessary experimental data,through the analysis of experimental data to conduct a safety evaluation.
Because of safety-oriented software system to assess the scene of the "realism" have high demands,so the need for the original visual system improvements.The use of multi-channel technology will be the expanse the single-channel visual system to multi-channel visual system,thereby increasing the scope of the driver's vision to improve the system of "immersion",improve the authenticity of the simulation of driver's perception in real environment and the credibility of the safety evaluation.
The safety-oriented distributed simulation system needs to simulate the interaction between vehicles in real environment,so the need to collect and exchange data between multiple nodes,which is real-time synchronization between nodes of simulation.In this system,the synchronous design to the two main areas:clock synchronization and data synchronization.Clock synchronization is implemented by transmit control information between nodes;the goal is to have the same local time among the nodes and facilitate system control and data collection.Data synchronization is implemented by exchange the control and status information between nodes under the certain control strategy,and corresponding entity node status on different node.
For data exchange and synchronization needs,the thesis design and implementation of reliable UDP-based transport mechanism.The mechanism is based on the UDP protocol to increase the response mechanism,retransmission and confirmation mechanism,packing/unpacking mechanism,in order to achieve reliable transmission of information.
Through requirement analysis of traffic safety evaluation,extracting the parameters needed for the safety evaluation,and designing method of the data collection to meet the requirements of the system.With database design technology,the experimental data can be stored in the database,easy for data analysis after experiment.
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