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 theorybased analysis and numerical simulations in a realistic 3D environment show the stability properties of the control methodologies. Copyright # 2007 John Wiley & Sons, Ltd.