Networked model predictive traffic control with time varying optimization horizon: The Grenoble South Ring case study

This work discusses the design of a networked traffic control scheme. We refer to the Grenoble South Ring traffic system, as case study, in which the control actions are computed in a control centre far from the traffic system and then sent, through a wireless communication channel, to the actuators placed along the road, i.e. on-ramp traffic lights in the considered case of ramp metering control. The communication channel is affected by delays and packet loss. In order to counteract the effects due to the transmission of the variable over the communication channel, we suggest to adopt a model predictive control (MPC) strategy based on the use of a buffer. Moreover, in order to limit the computational burden and improve the effectiveness of the proposal, the length of the optimization horizon of the predictive control algorithm, and, consequently, the buffer length, is updated relying on a delay estimation. The performances of the proposed approach are assessed in simulation relying on a traffic model the parameters of which are identified using data produced by a commercial microscopic simulator of the Grenoble South Ring traffic system. The capabilities of the considered control scheme when the system parameters vary and the transmitted signals are affected by time delays are highlighted.