本文選題：交通流 + 分支分析�。� 參考：《西北工業(yè)大學(xué)》2015年碩士論文

【摘要】：交通控制是緩解交通擁堵的重要手段之一。論文通過結(jié)合實(shí)際交通應(yīng)用背景研究道路擁堵問題,在分析交通擁堵產(chǎn)生機(jī)理的基礎(chǔ)上設(shè)計(jì)擁堵控制策略來代替人工調(diào)節(jié)控制,并從工程化角度設(shè)計(jì)實(shí)現(xiàn)小型化的交通流信息在線處理系統(tǒng)來實(shí)時(shí)監(jiān)控道路交通的運(yùn)行狀況,從而試圖獲得一種緩解交通擁堵的有效方法。論文主要工作總結(jié)如下:(1)針對(duì)現(xiàn)有交通微觀模型對(duì)實(shí)際道路車輛運(yùn)行狀況描述不足的問題,通過分析駕駛員心理和車輛動(dòng)力學(xué)特征對(duì)優(yōu)化速度模型進(jìn)行改進(jìn),結(jié)合實(shí)測(cè)數(shù)據(jù)對(duì)改進(jìn)后的模型進(jìn)行驗(yàn)證并進(jìn)行模型穩(wěn)定性分析,結(jié)果表明改進(jìn)后的模型能夠更好地對(duì)實(shí)測(cè)數(shù)據(jù)進(jìn)行擬合,可對(duì)實(shí)際交通運(yùn)行狀況進(jìn)行進(jìn)一步地準(zhǔn)確描述。(2)針對(duì)現(xiàn)有非線性分析方法對(duì)交通流應(yīng)用的局限性,將分支理論引入交通模型的非線性分析中,通過分析模型分支條件以及分支點(diǎn)鄰域內(nèi)的交通狀態(tài)變化來研究交通擁堵的作用機(jī)理。其中,微觀模型的分支分析采用傳統(tǒng)針對(duì)常微分方程的Hopf分析方法,而針對(duì)宏觀模型的偏微分方程表達(dá)形式,則是通過引入兩個(gè)等價(jià)的變量代換,如同將離散系統(tǒng)單位圓內(nèi)的穩(wěn)定性擴(kuò)大到整個(gè)復(fù)平面,將交通流問題轉(zhuǎn)化為系統(tǒng)穩(wěn)定性問題,然后再針對(duì)模型平衡點(diǎn)分支進(jìn)行重點(diǎn)分析。結(jié)果表明,分支的出現(xiàn)是導(dǎo)致交通失穩(wěn)進(jìn)而演化為交通阻塞現(xiàn)象的一個(gè)重要原因。(3)針對(duì)交通失穩(wěn)現(xiàn)象,分別以微觀改進(jìn)優(yōu)化速度模型和宏觀速度梯度模型為例來探討緩解交通擁堵的控制方法。其中,針對(duì)微觀模型的反饋控制方案,在理論分析反饋系數(shù)對(duì)控制模型穩(wěn)定性影響的基礎(chǔ)上進(jìn)行MATLAB仿真,結(jié)果表明通過合理調(diào)整反饋系數(shù)可有效緩解交通擁堵現(xiàn)象;針對(duì)宏觀模型的入口匝道模糊控制方案,構(gòu)造了以當(dāng)前路段偏離期望密度的差值和相鄰路段的密度差為輸入量、以匝道調(diào)節(jié)率為輸出量的二維模糊控制器,MATLAB仿真分析的結(jié)果表明,該控制方案對(duì)擁堵路段的交通狀況具有明顯改善作用。(4)從工程應(yīng)用角度搭建基于FPGA的交通流信息在線處理系統(tǒng),完成具有4片F(xiàn)PGA陣列結(jié)構(gòu)的6層電路板的PCB設(shè)計(jì)及硬件電路調(diào)試,基于QuartusⅡ開發(fā)工具完成交通流模型的FPGA仿真驗(yàn)證,并以宏觀模型為例進(jìn)行了系統(tǒng)整體功能的測(cè)試,結(jié)果表明系統(tǒng)能夠在線處理交通流數(shù)據(jù)并將數(shù)據(jù)結(jié)果通過顯示界面實(shí)時(shí)、直觀地顯示出來,滿足設(shè)計(jì)功能要求。
[Abstract]:Traffic control is one of the important means to alleviate traffic congestion.Based on the analysis of the mechanism of traffic congestion, a congestion control strategy is designed to replace manual control.A miniaturized online traffic flow information processing system is designed and implemented from the engineering point of view to monitor the traffic condition in real time so as to obtain an effective method to alleviate traffic congestion.The main work of this paper is summarized as follows: (1) aiming at the problem that the existing traffic microscopic models do not describe the actual road vehicles, the optimization speed model is improved by analyzing the drivers' psychology and vehicle dynamics characteristics.The improved model is verified with the measured data and the model stability is analyzed. The results show that the improved model can fit the measured data better.In view of the limitation of the existing nonlinear analysis method to traffic flow, branch theory is introduced into the nonlinear analysis of traffic model.The mechanism of traffic congestion is studied by analyzing the model bifurcation condition and the traffic state change in the neighborhood of the branch point.Among them, the branch analysis of microscopic model adopts the traditional Hopf analysis method for ordinary differential equation, and the partial differential equation for macroscopic model is expressed by introducing two equivalent variables.As the stability in the unit circle of discrete system is extended to the whole complex plane, the traffic flow problem is transformed into the stability problem of the system, and then the bifurcation of the equilibrium point of the model is analyzed emphatically.The results show that the emergence of branches is an important reason that leads to traffic instability and then evolves into traffic congestion.The control methods to alleviate traffic congestion are discussed by taking the microscopic improved optimal speed model and the macroscopic velocity gradient model as examples respectively.According to the feedback control scheme of micro model, MATLAB simulation is carried out on the basis of theoretical analysis of the influence of feedback coefficient on the stability of the control model. The results show that the phenomenon of traffic congestion can be effectively alleviated by adjusting the feedback coefficient reasonably.Aiming at the fuzzy control scheme of the entrance ramp in the macro model, the difference between the current road section deviation from the expected density and the density difference between adjacent sections is constructed as the input.MATLAB simulation results of 2-D fuzzy controller with ramp regulation rate as output show that,This control scheme can obviously improve the traffic condition of congested sections. (4) from the point of view of engineering application, an on-line traffic flow information processing system based on FPGA is built.The PCB design and hardware circuit debugging of the six-layer circuit board with four FPGA arrays are completed. The FPGA simulation verification of the traffic flow model is completed based on the Quartus 鈪，

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