Highway traffic density control based on the composite of CACMAC and PID controller

Vehicular density control on the motorway mainlines is a complicated problem and traditional control approaches of ramp metering prove to be unsatisfactory. In this paper, a composite control method based on credit assignment cerebellar model articulation controller (CACMAC) and proportional-integral-derivative (PID) controller is applied to highway density control. Firstly, a macroscopic traffic model is established to describe the evolution process of highway traffic flow accurately. Secondly, the principle and algorithm of CACMAC-PID compound control are studied in detail. Thirdly, road density controllers based on CACMAC-PID compound control are designed by combining the highway traffic model and a nonlinear feedback technology. In fact, vehicular density monitoring in the motorway mainlines is an output tracking control. Finally, simulation experiments are conducted to prove the validity and superiority of this composite control. Compared to CMAC-PID control, CACMAC-PID control has decreased the time to reach the steady-state value and improved the tracking effect. CACMAC-PID compound controllers can remove highway traffic congestion and stabilize mainline traffic flow.