Time-Varying Model-Based Observer for Marine Surface Vessels in Dynamic Positioning

Abstract

This paper deals with the problem of transient events in model-based observers for dynamic positioning of marine surface vessels. Traditionally, model-based observers experience a deterioration of performance during transients, and there is a give or take relationship between transient and steady state performance. To remedy this problem, we propose to use time-varying gains for a model-based observer. The gains are aggressive during transients to improve transient performance, and relaxed in steady state to lower the oscillations of the estimates. The proposed observer is analyzed with regard to stability. Its performance is verified in both a high-fidelity simulation model, and on experimental data with the research vessel (R/V) Gunnerus. In addition, a partial closed-loop validation with R/V Gunnerus has been performed.

Keywords

• Dynamic positioning
• Marine control systems
• Observers