Modified LOS Path Following Strategy of a Portable Modular AUV Based on Lateral Movement

Abstract

The portable modular AUV (Autonomous Underwater Vehicle), named ZFAUV, has the ability to move laterally. Its turning radius becomes smaller as the forward speed decreases. Based on this special maneuverability, a modified LOS (line of sight) path following strategy, integrating basic LOS and lateral movement, is proposed. The main idea of this strategy is to improve the path following performance through cross-track error and heading error. That is to say, the ZFAUV continues to move toward the current waypoint during a survey task. If ZFAUV deviates from the desired path due to disturbances from the wind, waves, current, or other uncertainties, it gradually returns to the desired path under lateral maneuverability. At the same time, in order to reduce overshoot after reaching the current waypoint, an arc transiting strategy and decelerating strategy (if necessary) are adopted. Through this strategy, the path following performance is greatly improved. Based on mathematical modeling, this strategy is simulated with a square path and a triangular path. The same paths are selected in lake experiments. The experimental results are in agreement with the simulation results, which demonstrate the validity of this strategy.