Development of a Dynamic Positioning System for the ReVolt Model Ship

Abstract

Autonomous surface vehicles are still in the early stages of development, and show great potential. These vessels can be used in different scientific and commercial operations, outperforming manned vessels in safety, endurance and cost efficiency.

A Dynamic Positioning (DP) control system has been developed for, and implemented on, a scale model of DNV GL s concept ship ReVolt. This model-scale ship, called ReVolt, is used as a test platform for an autonomous ferry, as well as an early test platform for sensors and control systems for autonomous vessels. As a result, this thesis primarily focus' on the functionality and implementation of the components and control system required to achieve DP capabilities on ReVolt.

A DP control system has been developed, consisting of a 3-Degree of Freedom reference filter and a Proportional-Integral-Derivative (PID) controller with a model-based feedforward from the reference. DNV GL's thrust allocation has been implemented and an Error-state Kalman Filter is developed. The DP control system is implemented on ReVolt's onboard computer, which runs the Robot Operating System (ROS) on top of a Linux shell. The control system has furthermore been simulated in Matlab to develop and test its functionality.

Extensive field tests has been completed, where the main objective was to achieve station keeping and low-speed maneuvering capabilities on ReVolt. Different setups in the thrust allocation and controller have been assessed to determine the best overall setup for ReVolt. In addition, the control system has been applied to a docking scenario to asses its applicability in docking.