Design of Dynamic Positioning Control System for an ROV with Unknown Dynamics Using Modified Time Delay Estimation

Abstract

Article History: Received: 31 Oct. 2018 Accepted: 27 Feb. 2019 In this paper, a control system is designed for dynamic positioning of an ROV with unknown dynamics, subject to external disturbances using passive arm measurements. To estimate uncertain dynamics and external disturbances, a new method based on time delay estimation (TDE) is proposed. The proposed TDE, not only maintains the advantages of conventional TDE, but also eliminates its sensitivity to sensor noise and fast-varying external disturbances which in turn, results in smooth control signal. The proposed control system is considered as a nonlinear PD-type controller together with feedforward of estimated dynamics and disturbances. This structure presents good performance against uncertainties and external disturbances which is guaranteed via stability analysis presented. To evaluate the performance of proposed TDE, simulations are conducted and comparison are made with conventional TDE. Besides, the performance of the proposed control system is compared with conventional time delay controller (TDC) and PID controller to verify its performance. Simulations show high accuracy and superior performance of the proposed control system.