An output feedback nonlinear decentralized controller for unmanned vehicle co-ordination

This paper presents vision-based control strategies for decentralized stabilization of unmanned vehicle formations. Three leader-follower formation control algorithms, which ensure asymptotic co-ordinated motion, are described and compared. The first algorithm is a full state feedback nonlinear controller that requires full knowledge of the leader's velocities and accelerations. The second algorithm is a robust state feedback nonlinear controller that requires knowledge of the rate of change of the relative position error. Finally, the third algorithm is an output feedback approach that uses a high-gain observer to estimate the derivative of the unmanned vehicles' relative position. Thus, this algorithm only requires knowledge of the leader-follower relative distance and bearing angle. Both data are computed using measurements from a single camera, eliminating sensitivity to information flow between vehicles. Lyapunov's stability theory-based analysis and numerical simulations in a realistic 3D environment show the stability properties of the control methodologies. Copyright (c) 2007 John Wiley & Sons, Ltd.