面向长匝道的高速公路入口控制模型

A Control Model with Local Feedback for Long On-ramp Metering

在高速公路入口处,控制点通常与道路主线通过长匝道相连,导致控制距离较长,在传统匝道控制器的作用下,过长的控制距离容易使主线车流产生振荡。而此情况类似于电子放大系统中的自激振荡,因此引入电子技术中的频率补偿思想,构造一种新的入口匝道控制器以解决该问题。基于频率补偿的控制器,考虑到了在饱和阶段所产生的振荡信号,人为地对反馈控制信号引入一定的相位移用于破坏振荡产生的条件,可有效地抑制主线交通流发生波动。而对于在进行频率补偿的过程中所产生的过度补偿现象,新的算法加入了补偿因子来消除过度补偿而产生的振荡。仿真试验表明,新的控制器能够快速地将交通流调整到期望状态,可以适应匝道控制点与下游检测点位置的任意变化,相对于传统控制器,主线交通流的振荡现象得到明显消除。

At the entrance of freeways,the mainline and the control points are usually connected by an on-ramp,which usually apart from each other over a long distance.This distance usually results in the oscillation of mainline traffic flow under traditional on-ramp control.This fact is very similar to the self-excited oscillation in electronic system.Therefore,a new on-ramp controller is proposed with the frequency compensation.Considering the oscillated signal generated under the saturated scenario,the proposed controller aims to remove the reasons generating such oscillations by artificially introducing aphase shift signal feedback,so that it can effectively inhibit the fluctuation of mainline traffic flow.In addition,the new algorithm can solve the problems related to over-compensation shown in the process of the frequency compensation.Simulation results show that the new controller can be used to quickly adjust traffic flow to the expected state.It is also highly adaptive to randomly changes in the position of the ramp controller and the downstream detector.Compared with the traditional controller,the oscillation of mainline traffic can be significantly reduced by using this new controller.