String stability margin of cyclic vehicle platoons with variable communication range

Abstract

This paper proposes a new metric in regard to the string stability margin (SSM) of cyclic vehicle platoons and its connection with the platoon’s communication range r and the vehicle dynamics L(s). Unlike the previous works including Stüdli et al. (2018) in which a limited class of L(s) is discussed with no clear concept of SSM, in this paper SSM denoted by α∗ is unambiguously defined via the singular value capturing the platoon’s robustness with respect to gain/phase or coprime factor uncertainties in the network. It is then shown that SSM depends on the network connectivity λ2 which increases with r, as well as the geometric shape of Nyquist plot of L(s). Such dependency is analysed for three different types of L(s), yielding the maximum SSMs at different communication ranges.