Output-Feedback Consensus-Formation Control of Nonholonomic Vehicles With Input Constraints and Time-Varying Delays

We provide a solution to the consensus-based formation control problem of multi-agent nonholonomic vehicles, under the assumption that the magnitudes of control inputs must satisfy certain pre-imposed bounds, to avoid saturation of the actuators. We consider that the communications are affected by time-varying delays and the vehicles lack velocity measurements. The desired control objective is that all the vehicles converge to a given desired formation and that they reach consensus on the localization of the center of such formation and on their orientations. The control architecture exploits several features. From a control viewpoint, the systems' dynamics are split into their angular- and linear-motion parts, so each of these is driven by a separate distributed dynamic output-feedback controller, passively interconnected to the plant via a virtual spring. From a network-topology viewpoint the overall networked system contains two layers of interconnections with undirected graphs. Finally, from an analytical viewpoint, each vehicle-controller closed-loop-system may be regarded as a cascade with a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{\delta }$</tex-math></inline-formula>-persistently exciting interconnection, which ensures the achievement of the control goal, in spite of the nonholonomic constraints.