  This article provides an overview of the design of nonlinear feedback Cruise
Controllers (CCs) for automated vehicles on lane-free roads. The feedback
design problem is particularly challenging because of the various state
constraints (e.g., collision-free movement, road geometry, speed limits) as
well as the nature of the control objective (globally stabilizing distributed
controllers that require measurements from neighboring vehicles only).
Therefore, the resulting nonlinear control system is defined on an open set
(not necessarily diffeomorphic to a linear space) for which the set of desired
equilibria is non-compact. The proposed design of the CCs is based on
energy-like control Lyapunov functions which combine potential functions with
kinetic energy terms and other appropriate penalty terms. The feedback design
in the microscopic level is accompanied by the derivation of the corresponding
macroscopic traffic flow models. Explicit relations are established between
selectable CC features and the obtained macroscopic traffic flow
characteristics. This facilitates the active design of efficient traffic flow
with desired properties, i.e., the construction of artificial traffic fluids.
