An Output Feedback Controller with Improved Transient Response of Marine Vessels in Dynamic Positioning*

:An output feedback controller for dynamic positioning (DP) of marine surface vessels is developed. The proposed algorithm has good performance during transients as well as good steady state performance. The method achieves this by a flexible injection gain in the bias estimation dynamics in the observer. In addition, the traditional integral action is replaced by a filtered bias estimate from the observer. Both these elements combined provide good DP performance in transients, as well as calm behavior in steady state. A simulation study is performed showing the benefit of the proposed output feedback controller, and a stability analysis is performed to show uniform asymptotic stability.