Nonlinear-Observer-Based Design Approach for Adaptive Event-Driven Tracking of Uncertain Underactuated Underwater Vehicles

Abstract

A nonlinear-observer-based design methodology is proposed for an adaptive event-driven output-feedback tracking problem with guaranteed performance of uncertain underactuated underwater vehicles (UUVs) in six-degrees-of-freedom (6-DOF). A nonlinear observer using adaptive neural networks is presented to estimate the velocity information in the presence of unknown nonlinearities in the dynamics of 6-DOF UUVs where a state transformation approach using a time-varying scaling factor is introduced. Then, an output-feedback tracker using a nonlinear error function and estimated states is recursively designed to overcome the underactuated problem of the system dynamics and to guarantee preselected control performance in three-dimensional space. It is shown that the tracking error of the nonlinear-observer-based output-feedback control system exponentially converges a small neighbourhood around the zero. Efficiency of the resulting output-feedback strategy is verified through a simulation.

Fast Terminal Sliding Control of Underactuated Robotic Systems Based on Disturbance Observer with Experimental Validation

“…Underactuated systems are categories of nonlinear dynamic systems which have fewer number of actuators than degrees of freedom [1][2][3][4][5]. The stabilizer and tracker design problems of these dynamical structures involve wide investigation due to their application in flexible manipulators [6], marine vessels [7], robotics [8,9], aircraft assembly [10], hovercraft [11], legged locomotion [12], overhead crane [13], satellite [14], rigid spacecraft [15], inverted pendulum [16], aeroelastic wing section [17], underwater vehicles [18], surface vessels [19], quad-rotors [20,21], flexible joint robots [22], cranes [23], visual servoing [24], proprioceptive tactile sensing [25], vertical take-off and landing drones [26] etc.…”