From vehicular platoons to general networked systems: string stability and related concepts

Networked systems and their control are highly important and appear in a variety of applications, including vehicle platooning and formation control. Especially vehicle platoons have been intensively investigated. An interesting problem that arises in this area is string stability, which broadly speaking means that an input signal amplifies unboundedly as it travels through the vehicle string. However, various, not necessarily equivalent, definitions are commonly used. In this paper, we aim to formalise the notion of string stability and illustrate the importance of those distinctions on simulation examples. A second goal is to extend the definitions to general networked systems.