Research On Traffic Density And Speed Control Method Based On Improved Macroscopic Traffic Flow Model

In the environment of automatic expressway,the expressway system can use the detection equipment to collect the real-time information of the road,and then effectively control the traffic flow through the intelligent terminal.The system mainly includes drivers,vehicles controllers and road infrastructure,etc.,which provides an effective method for alleviating traffic conges-tion caused by traffic events,and the research is of great significance.Based on the macroscopic traffic flow model,this paper focuses on the design and comparison of the controller and the improvement of the macroscopic traffic flow model Research,as follows:1.A model predictive control(MPC)method based on macroscopic traffic flow model is proposed to solve the problem of traffic congestion on expressways.In order to solve the uncer-tainty caused by ramp,this method takes the traffic flow density of each section as the control target,designs the MPC algorithm based on the macroscopic traffic flow model,and obtains the control input by solving the optimization problem to ensure better control effect.Simula-tion results show that compared with the existing variable structure control(VSC)method,the proposed method has better rapidity,eliminates the chattering phenomenon in the VSC method,and effectively alleviates the traffic congestion.2.In order to make the model more suitable for the MPC algorithm,this paper improves the traditional macroscopic traffic flow model,transforms the traffic flow density and speed into state variables through certain substitution,and deduces the formula to obtain a state space macroscopic traffic flow model.The results show that compared with the traditional macro-scopic traffic flow model,the state space macroscopic traffic flow model is more intuitive and simple,and is more suitable for MPC theory and design method,saving a lot of time and im-proving the research efficiency.3.For the expressway system,this paper designs VSC and MPC algorithms based on the state space macroscopic traffic flow model.The VSC algorithm takes the traffic flow density as the control target,controls the density indirectly through the traffic flow speed,and obtains the control input according to the discrete approach law in the VSC algorithm.The MPC al-gorithm can control the density and speed of traffic flow at the same time for the problems of multivariable and control quantity constraints,so as to realize the effective control of traffic flow.The simulation results show that,compared with the VSC algorithm,the MPC algorithm can make the density and speed of the traffic flow approach the expected value more quickly,and has better stability without chattering phenomenon,so as to avoid the occurrence of road congestion.Based on the traditional macroscopic traffic flow model,this paper aims at the expressway system by improving the model,MPC and VSC algorithm design and other means to effectively alleviate the traffic congestion.In general,the MPC method proposed in this paper has fast control effect,eliminates chattering phenomenon,and has strong stability.The research results of this paper can further improve the theoretical basis of traffic flow control and better solve the problem of traffic congestion.