Nonlinear feedback ramp controller in freeway based on fuzzy logic
高速公路非线性反馈模糊逻辑匝道控制器

The on-ramp control is considered as an important component of freeway traffic control and intelligent transport systems,but the results of existing on-ramp control are not satisfactory.A nonlinear feedback method is proposed for on-ramp metering by using fuzzy logic.The freeway traffic flow dynamic model is built.Based on the model and in conjunction with the fuzzy logic theory,the nonlinear feedback ramp controller is designed. The ramp metering rate is determined by the fuzzy control based on the density tracking error and error variation.Triangle curves are used for the membership functions of the fuzzy variables.The rule base including 56 fuzzy rules is also established.Finally,the control system is simulated in MATLAB software.The result shows that the controller designed has good dynamic and steady-state performance,and can achieve a desired traffic density along the mainline of a freeway.This method is effective to the on-ramp control.