Trajectory Tracking Motion Control System for Observation Class ROVs

This paper proposes a MCS (Motion Control System) with trajectory tracking capability for observation class ROVs (Remotely Operated Vehicle) used to carry out automated high-resolution image capturing missions, e.g. inspections, mappings, and surveys. The trajectory tracking capability is a key feature to enable the end-users of the ROV technology to acquire sequential high-quality images at proper pace to construct consistent representations of the objects or of the environments of interest. Four degrees-of-freedom are controlled – surge, sway, heave, and yaw. The MCS consists of an output feedback control system that is composed of a high-gain state observer and a MIMO (Multiple-Input-Multiple-Output) PID (Proportional-Integral-Derivative) controller, that works aided by reference feedforward. Plant linearisation is performed aiming at improving the tracking performance. Stability and satisfactory performance for suitable and smooth reference trajectories are attained despite the presence of unmodelled dynamics, plant parameter variations, measurement noise, and environmental disturbances. Simulated results based on the model of the NTNU's ROV Minerva are presented.