Modeling freeway network by using dynamic graph hybrid automata and estimating its states by designing state observer

This paper considers a new modeling method and traffic state estimation for a freeway network. Firstly, we propose a new modeling method, which is called Dynamic Graph Hybrid Automata (DGHA), to describe the evolution law of the freeway network. In the model, the traffic dynamics are described by the Modified Cell Transmission Model (MCTM), where the cells are expressed by hybrid automata, and multi-mode switching expressions are introduced into the connections among these cells. The proposed DGHA model is modularized and easily-extensible. Combination between cells is implemented automatically by an algorithm. By using the modeling method and the algorithm of combination between cells, one can establish the freeway network models with any topology structure. Secondly, a switched state observer is designed to estimate the traffic states of the freeway network. Finally, the proposed method is applied to Beijing third ring freeway, which shows the effectiveness of the proposed modeling method and the accuracy of the state estimation.