Design of Contractive Output Feedback Controllers For Filtered Backstepping

This paper proposes a novel observer based filtered backstepping controller for a class of nonlinear systems. For this purpose, the contraction theory based tools are exploited to design an exponentially convergent linear time varying observer. The proposed observer satisfies the sufficient observability condition and the resulting output feedback controller assures ultimate boundedness of closed loop trajectories. The use of partial contraction concept for convergence analysis serves a dual purpose. It relaxes the choice of high gain filter parameter, whose magnitude needs to be constrained inside a conservative range in Lyapunov based approaches. Moreover, the exact dependency between closed loop system performance and design parameters are quantified in terms of known constants. The developed technique is successfully simulated for a D.C. motor driven manipulator system. (C) 2018, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.