Reference Tracking Control for Maneuvering Vessels considering Input Delay

Abstract

Due to increasing vessel sizes and traffic volumes, maneuvering is becoming more and more challenging. Therefore, bridge personnel should be assisted by providing control systems for maneuvering. In addition to an expected improvement in safety and efficiency, automatic maneuvering is also relevant with regard to future autonomous shipping. This paper contributes to position control and heading control, which form the basis for higher-level guidance systems. An extension of the widely used dynamic positioning approach is presented to realize integral reference tracking. This provides the capability to follow a predefined trajectory.The coupled acceleration behavior of the vessel in terms of a full mass matrix is taken into account by a compensation approach, so that a SISO controller design becomes applicable.In the case of the investigated application, there was a significant input delay, which led to greatly reduced control performance and oscillation around the reference value. These problems were solved by applying the so-called reduction transformation approach to the use case of a maneuvering vessel. The time constant of the closed loop system is chosen as the design parameter of the controller design. It represents the choice between performance and economy, which is made by the operator. The realization of the demanded time constant is implemented by a simple optimization loop that yields the actual feedback gain for linear quadratic optimal control.Real-world tests of the presented system were carried out in a model basin with a scale model of an offshore supply vessel to validate the functionality of the entire control system.