Research On Integrated Control Strategy Of Expressway Based On MPC

With the combination of two or more control strategies,integrated control for expressway can effectively improve traffic congestion and make traffic flow safer and steadier.However,there are limited researches on the analysis of the factors of integrated control,and the distinction between the integrated control strategies based on different traffic flow models has yet been profoundly researched,also the classical macro traffic flow models and control algorithms need to be ameliorated.Whereas the above problems,this paper conducted a comprehensive research from the aspects of mechanism,technology,application and effect.The characteristics of expressway were analyzed,and the deterioration process of traffic flow was expounded.It was pointed out that integrated control should be an effective measure to avoid the breakdown of traffic flow,then through methods of literature review and mechanism analysis,factors were screened out from the aspects of theoretical method,the application of technology and external environment.The control algorithms related to ramp metering and variable speed limit were extended separately,the PI-ALINEA control algorithm was improved,and an adaptive ramp control system was proposed to automatically update the target density.The MTFC-VSL algorithm was ameliorated in three ways:updating the target density in real time,considering the actual vehicle compliance rate,introducing the model predictive control frame.Next the integrated control framework based on MPC was constructed.For optimization of the control strategy,a multi-targets GA algorithm was designed.Considering ramp metering and variable speed limit respectively,the classical models METANET and CTM were modified,and the method for model calibration and verification were designed.Two MPC integrated control strategies based on different traffic flow models were proposed with the introduction of the two extened taffic flow models.A simulation experiment was carried out.Four control scenes were set up:no control,ramp metering,variable speed limit and integrated control.The two strategies were compared and analyzed from the aspects of traffic efficiency and traffic safety.The results show that the two traffic flow models can simulate the actual road traffic flow,the MPC integrated control strategy based on METANET achieve a better performance.