Impact of Disturbances on Mixed Traffic Control with Autonomous Vehicles

TL;DR

This paper analyzes how different types of disturbances affect mixed traffic flow control with autonomous vehicles on a ring road, revealing that velocity disturbances cause uncontrollable growth in traffic variance, while acceleration disturbances are manageable.

Contribution

It demonstrates that velocity disturbances lead to uncontrollable and unbounded traffic flow variability, whereas acceleration disturbances can be effectively controlled, providing new insights into disturbance impacts in mixed traffic systems.

Findings

Velocity disturbances cause unbounded variance growth.

Acceleration disturbances are controllable and benign.

System stability depends on disturbance type.

Abstract

This paper investigates the impact of disturbances on controlling an autonomous vehicle to smooth mixed traffic flow in a ring road setup. By exploiting the ring structure of this system, it is shown that velocity perturbations impacting any vehicle on the ring enter an uncontrollable and marginally stable mode defined by the sum of relative vehicle spacings. These disturbances are then integrated up by the system and cannot be unwound via controlling the autonomous vehicle. In particular, if the velocity disturbances are zero-mean Gaussians, then the traffic flow on the ring will undergo a random walk with the variance growing indefinitely and independently of the control policy applied. In contrast, the impact of acceleration disturbances is benign as these disturbances do no enter the uncontrollable mode, meaning that they can be easily regulated using the autonomous vehicle. Our results support and complement the existing theoretic analysis and field experiments.