Velocity and Disturbance Robust Nonlinear Estimator for Autonomous Surface Vehicles Equipped With Position Sensors

This brief presents a robust nonlinear state estimator for autonomous surface vehicles, where the movement is restricted to the horizontal plane. It is assumed that only the vehicle position and orientation can be measured, being the former affected by bounded noises. Then, under some fair standard assumptions concerning the maximum velocities and acceleration rates of the vehicle, the estimator is able to reconstruct not only the velocities but also the lumped generalized disturbances that cluster external disturbances, nonlinearities, and unmodeled dynamics. The observer is easily tunable by the user, with a set of four scalars, two of them related to the velocity of convergence of the estimator, and other two parameters to set the desired tradeoff between noise sensitivity and disturbance rejection. Several simulations with a well-known test-bed craft are provided to show how the proposed algorithm outperforms previous ones in the literature under realistic environmental conditions.