Benefits of V2V Communication for Autonomous and Connected Vehicles

In this paper, we investigate the benefits of vehicle-to-vehicle (V2V) communication for autonomous vehicles and provide results on how V2V information helps reduce employable time headway in the presence of parasitic lags. For a string of vehicles adopting a constant time headway policy and availing the on-board information of predecessor’s vehicle position and velocity, the minimum employable time headway (<inline-formula> <tex-math notation="LaTeX">$h_{\min }$ </tex-math></inline-formula>) must be lower bounded by <inline-formula> <tex-math notation="LaTeX">$2\tau _{0}$ </tex-math></inline-formula> for string stability, where <inline-formula> <tex-math notation="LaTeX">$\tau _{0}$ </tex-math></inline-formula> is the maximum parasitic actuation lag. In this paper, we quantify the benefits of using V2V communication in terms of a reduction in the employable time headway: 1) If the position and velocity information of <inline-formula> <tex-math notation="LaTeX">$r$ </tex-math></inline-formula> immediately preceding vehicles is used, then <inline-formula> <tex-math notation="LaTeX">$h_{\min }$ </tex-math></inline-formula> can be reduced to <inline-formula> <tex-math notation="LaTeX">${4\tau _{0}}/{(1+r)}$ </tex-math></inline-formula>; 2) furthermore, if the acceleration of ‘<inline-formula> <tex-math notation="LaTeX">$r$ </tex-math></inline-formula>’ immediately preceding vehicles is used, then <inline-formula> <tex-math notation="LaTeX">$h_{\min }$ </tex-math></inline-formula> can be reduced to <inline-formula> <tex-math notation="LaTeX">${2\tau _{0}}/{(1+r)}$ </tex-math></inline-formula>; and 3) if the position, velocity, and acceleration of the immediate and the <inline-formula> <tex-math notation="LaTeX">$r$ </tex-math></inline-formula>-th predecessors are used, then <inline-formula> <tex-math notation="LaTeX">$h_{\min } \ge {2\tau _{0}}/{(1+r)}$ </tex-math></inline-formula>. Note that cases <xref rid="deqn2" ref-type="disp-formula">(2)</xref> and <xref rid="deqn3" ref-type="disp-formula">(3)</xref> provide the same lower bound on the minimum employable time headway; however, case <xref rid="deqn3" ref-type="disp-formula">(3)</xref> requires much less communicated information.