【作者】 张杰；

【导师】 贺国光；

【作者基本信息】 天津大学 ， 管理科学与工程， 2007， 博士

【摘要】 城市交通控制系统是智能交通系统中的一个重要组成部分,它在改善城市交通秩序、提高交通安全以及减少环境污染等方面发挥着举足轻重的作用。控制理论认为,设计控制系统时主要依据的是被控对象的动态特性,因此要实现城市交通的有效控制,对城市交通流对象动态特性的研究是不可回避的。然而由于交通流本身的不确定性和复杂性,真正从控制理论角度出发研究交通流的动态特性问题,一直是交通控制领域研究的一个难点。本论文主要进行的工作可以概括为以下几个方面:1、通过对现有城市交通控制方法的评述,重点指出了这些方法存在的缺陷,由此说明了研究城市交通流对象动态特性的重要意义。被控对象的传递函数是系统动态特性的数学表达式,然而由于城市交通流对象的非线性和时变性,是不能直接对其建立一个统一的数学模型的,因此提出在一定的条件下将城市交通流还原分解为大量离散线性定常子系统来研究其动态特性的方法。基于系统辨识的方法建立各子系统的传递函数,利用方程的系统参数和结构参数定量地分析其动态特性,最后再用系统科学的思想来看待和分析整个城市交通流对象。2、提出了描述城市交通流对象的一般模型结构,确定了描述单路口和以干线交通流为代表的城市路网交通流的典型动态环节。以仿真试验作为研究手段,通过设计不同的仿真试验内容,设定不同的仿真试验条件,获得了不同条件下的不同仿真交通流的输入输出数据,基于系统辨识的方法分别建立了单路口和干线交通流的传递函数模型。基于辨识模型对单路口和干线交通流的动态特性进行了分析。从试验结果总结出一般性的结论:城市交通流的周期控制通道传递函数为三阶系统;绿信比控制通道传递函数为二阶系统;相邻交叉口之间相位差控制通道传递函数为四阶系统。城市交通流各动态环节均是稳定的,输出响应均为振荡收敛的脉冲序列。3、为了使本文对城市交通流动态特性的研究成果便于应用于城市交通控制,提出了一种基于交通流动态特性的交叉路口交通流状态分类方法,将交叉路口处交通状态划分为三个等级:自由流,同步流和堵塞流。设计了城市交通变结构最优控制系统的基本结构,给出了该系统中最优控制器的设计方法,为现代控制理论方法在城市交通控制中的应用开辟了崭新的一页。更多还原

【Abstract】 As an important subsystem of Intelligent Transport Systems, the urban traffic control system has a significant effect on reforming traffic order, improving traffic safety, decreasing environment pollution and so on. From the point of view of control theory, the control system design methods are mainly based on the dynamic characteristics of the controlled object. Therefore, in order to control urban traffic flow more effectively,its dynamic characteristics must be studied. However, due to the intrinsically uncertainty and complication of urban traffic flow, the study of its dynamic characteristics based on control theory is a difficult job all along.Some main aspects, which were studied in this dissertation, are presented as follows:The importance of studying the dynamic characteristics of urban traffic flow was pointed out based on the limitations of the existing urban traffic control methods. The transfer function of a controlled object is a mathematical expression of its dynamic characteristics. However, it cannot establish a uniform transfer function for urban traffic flow directly due to its nonlinear and time-varying characters. A method was presented to study the dynamic characteristics of urban traffic flow, which was based on decomposing it into many discrete linear constant subsystems under certain conditions. The transfer functions of these subsystems were established based on system identification methods. Their dynamic characteristics were analyzed quantificational by the system and structure parameters of the transfer functions. At last, using the dynamic characteristics of these subsystems, the urban traffic flow was looked upon as one system based on the Systems Science.A general model structure was presented to describe urban traffic flow. Some typical dynamic units were presented to describe the traffic flow of an intersection and main roads, which are the representation of the road network traffic flow. The study was carried out by means of simulation experiments. In order to get the input/output data of the simulated traffic flow under different conditions, many different simulation experiments were designed. Using the input/output data, the transfer functions of the traffic flow of an intersection and main roads were established based on the methods of system identification. Therefore, the dynamic characteristics of the traffic flow of an intersection and main roads were analyzed. Some general conclusions were got: the transfer functions of the Cycle control channels are three-order systems; the transfer functions of the Split control channels are two-order systems; the transfer functions of the Offset control channels between adjacent intersections are three-order systems; all the dynamic units of urban traffic flow are stable, and their output pulse response sequences are oscillated and convergent.In order to develop the research results of the dynamic characteristics of urban traffic flow into urban traffic control practice, a method to classify urban traffic flow states at intersections based on its dynamic characteristics was presented. Based on its dynamic characteristics parameters, the traffic flow of an intersection can be classified into three different states: free flow, synchronized flow and wide moving jam. Moreover, the basic architecture of urban traffic variable structure and optimal control system was designed based on variable structure control and optimal control theory. The design method of the optimal controller of the new control system was presented. The proposal of the new control system is a new vision of the application of modern control theory in the urban traffic control field.更多还原