Analysis and design of reliable control systems for urban traffic networks

This work deals with the analysis and design of reliable traffic control systems for urban transportation networks. The dynamics of queue length in front of the intersections are captured by a nonlinear state space model where a limit-reset function is introduced to maintain the non-negativity of the queues for traffic conditions ranging from undersaturation to oversaturation. A reliable control system is then synthesized to maintain system integrity (stability and vehicle flow regulation) under partial system failure brought about by local faults such as sensor and actuator failure, vehicle accidents and severing of communication links. It is shown that the reliable conditions are rather mild and can readily be satisfied by a properly designed decentralized propotional-integral-type controller. A detailed case study is also included in this work to demonstrate the properties of a reliable traffic network.