Robust CACC in the Presence of Uncertain Delays

Abstract

Cooperative adaptive cruise control employs inter-vehicle wireless communication to safely drive at short inter-vehicle distances, which improves road throughput. The underlying technical requirement to achieve this benefit is formulated by the notion of string stability, requiring the attenuation of the effects of disturbances in upstream direction. However, wireless communication delays significantly compromise string stability. In addition, the time delay is uncertain due to the inherent characteristics of wireless communication. Therefore, a controller design method is desired for a string-stable cooperative adaptive cruise control system, which considers uncertain communication delays. To this end, the string stability requirement is integrated into a μ synthesis approach. Being different from only considering the upper bound of the time delay, the whole range of time delays is taken into account in the controller design. Therefore, the proposed method allows for CACC system behaviour predictable, and rigorously guarantee string stability for all possible uncertain delays. The results are validated with simulations.