Path-Following Control Method for a Kelp Harvesting Vessel Based on ELOS

Abstract

A reduced-order extended-state-observer-based line-of-sight (ELOS) method is proposed for robust path following of a low-speed kelp harvesting vessel subject to sideslip. The observer estimates the equivalent lateral disturbance without re-estimating the measurable cross-track error, and the reconstructed sideslip corrects the reference heading. Noise-free straight- and curved-path cases are retained, and a 20 -run Monte Carlo test adds time-varying current, harvesting-load fluctuations, and navigation noise. Against LOS, integral LOS, adaptive LOS, and full-order ESO-ELOS under identical conditions, the proposed method obtains a cross-track root-mean-square error of 0.117 m with a standard deviation of 0.001 m, reductions of 15.0, 37.9, 33.1, and 7.2 percent, respectively. Its maximum error is 0.218 m and its sideslip-estimation root-mean-square error is 0.544 degrees. A gain sweep identifies 0.30 per second as a practical tracking-noise compromise. The results demonstrate improved disturbance rejection with one dynamic observer state.