Research On Joint Control Of On-Ramp Metering And Main Line Speed Guidance In Expressway Based On MPC

The urban expressway system is a fast access function for the long-distance travel of the main skeleton in the urban road network.The traffic efficiency of the expressway system will affect the traffic efficiency of the entire city.The idea that traffic control can improve the traffic efficiency of urban expressway systems has been fully confirmed.The main control methods include on-ramp metering and speed guidance control.At present,most of the researches on these two control methods have problems such as unclear application conditions and unsystematic methods.In this paper,on-ramp metering and speed guidance control are combined effectively.Based on the research of on-ramp metering algorithm,speed guidance control,macroscopic traffic flow model and model predictive control,a joint control method based on MPC for on-ramp metering and speed guidance control of urban expressway is proposed.In this paper,the ALINEA algorithm and its related extended algorithm are systematically summarized,including advantages and disadvantages,applicability,etc.,which provides a reference for the selection of ramp metering algorithms in practical engineering applications.Based on this,the improvement of ALINEA algorithm is researched,which improves the effectiveness of the algorithm in the queuing control of the ramp and the rationality of the algorithm in the case of multilane.In terms of speed guidance control,this paper first summarizes two speed guidance control methods,and conducts sensitivity analysis for speed guidance control at macro and micro levels.The relationship between speed guidance control and traffic efficiency and traffic safety level under different controlled vehicle ratios is obtained.From the quantitative point of view,the traffic efficiency and traffic safety level are used as indicators to study the applicable conditions of speed guidance control at different traffic demand levels.Aiming at the METANET model of expressway macroscopic traffic flow,this paper analyzes the influence of the joint control of variable speed limit and on-ramp metering.Based on this,the model structure is changed to make it more suitable for expressing the traffic flow state under joint control situation and a dynamic ramp control scheme based on waiting time clustering is designed.Finally,the MPC joint control model is established based on the improved METANET model,and the control model is solved by the genetic algorithm NSGAII.Through the cooperation of VISSIM,MATLAB and other software,the 7.1-kilometer section of Shenzhen Beihuan Expressway was used as the section to carry out the simulation.The results show that the proposed control method can effectively improve traffic efficiency and traffic safety.