Semi-active Groundhook Control of Offshore Tension Leg Platforms using TMD with Optimized Parameters and MR Damper under Multiple Hazards

Abstract

The purpose of the current study is to recommend an offshore tension leg platform (TLP) semi-active control system to lessen vibrations caused by various risks, such as the wind load and regular and irregular waves. State-of-the-art indicates that there has not been much study on semi-active management of offshore TLPs exposed to numerous hazards while taking into account system nonlinearities and employing a control method that is resilient to uncertainty. An Augmented Velocity-Displacement Based Groundhook (AVDB-GH) semi-active control scheme using MR dampers, which is an improvement over the displacement based Groundhook (DB-GH) control algorithm is proposed. The proposed controller uses a semi-active TMD (SATMD) consisting of a passive tuned mass damper (TMD) and two semi-active magneto-rheological (MR) dampers as the control devices. Constrained non-linear optimization is used to determine the SATMD's optimized parameters in order to produce the best control performance. A significant reduction in surge response of TLP is observed both in the time domain and the frequency domain. Compared to the SATMD using the usual DB-GH algorithm, the suggested control strategy more successfully decreases the key response variables—deck displacement, power spectral density, and acceleration. The effectiveness of the controller is better for regular waves than for irregular waves and wind forces. Because the performance of the controller is unaffected by changes in the mass and stiffness of the TLP, the controller can be regarded as robust.