NONLINEAR OBSERVERS FOR TRACKING AND NAVIGATION OF MARINE SYSTEMS: DESIGN BASED ON MOTION LINEARIZATION

In this paper nonlinear estimation problems commonly found in marine systems are addressed, supported on a methodology recently introduced for the design of exponentially stable nonlinear observers for non-autonomous time- varying nonlinear systems (Oliveira, 2007). An extra degree of freedom is exploited in a new synthesis methodology to compute the nonlinear estimator gains, based on the solution of a set of linear equations related to the underlying Lyapunov equation. A nonlinear tracker and a complementary navigation system in the plane illustrate the design procedure and allow the performance assessment obtained with the proposed method