Motion control of a non-holonomic marine robot for seeking and tracking an isoline of an unknown environmental field
Abstract
An autonomous mobile non-holonomic surface marine robot of a dual-engine catamaran type operates under unknown disturbances from a dynamic medium. The robot has to find and display a spatially distributed phenomenon (e.g., a polluted area) given by an unknown environmental field (exemplified by the distribution of the concentration of a pollutant). To this end, the robot should find and arrive at the isoline (level set) where the field assumes a given critical value, and then repeatedly track this isoline. The robot acquires data on the field only by sensing the field value at the current location; the field gradient is unavailable for measurements. A novel non-gradient-based sliding-mode navigation algorithm is proposed that solves the mission. The convergence and performance of the algorithm are justified via computer experiments using T. Fossen’s 6-DOF realistic catamaran simulator.