Leader-follower simultaneous tracking-agreement formation control of nonholonomic vehicles

We present a unified decentralized force-controller that solves both, the leader-follower tracking and agreement formation control problems for a group nonholonomic mobile vehicles interconnected via a directed spanning-tree graph topology. The control strategy is inspired by and extends the main results in [20] which apply only in the one-leader-one-follower scenario. We assume that the leader velocities may be persistently exciting (in the tracking case) or vanishing (in the agreement scenario). As it is common in the literature our controller is composed of an inner loop at the velocity kinematics level and an outer-loop at the dynamics level. We establish robustness of the kinematics closed-loop system in the sense that the convergence of the formation errors is preserved, under the action of any velocity-controller that guarantees that the velocity errors are square integrable.