Semi-Active Groundhook Control of Offshore Tension Leg Platforms Using Tuned Mass Damper With Optimized Parameters and Magneto-Rheological Damper Under Multiple Hazards

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 windload and regular and irregular waves. State-of-the-art indicates that there has not beenmuch study on semi-active management of offshore TLPs exposed to numerous hazardswhile taking into account system nonlinearities and employing a control method that isresilient to uncertainty. An augmented velocity-displacement-based groundhook (AVDB-GH) semi-active control scheme using magneto-rheological (MR) dampers, which is animprovement over the displacement-based groundhook (DB-GH) control algorithm, isproposed. The proposed controller uses a semi-active tuned mass damper (SATMD) consist-ing of a passive tuned mass damper (TMD) and two semi-active MR dampers as the controldevices. Constrained nonlinear optimization is used to determine the SATMD's optimizedparameters in order to produce the best control performance. A significant reduction insurge response of TLP is observed both in the time domain and the frequency domain. Com-pared to the SATMD using the usual DB-GH algorithm, the suggested control strategy moresuccessfully decreases the key response variables-deck displacement, power spectraldensity, and acceleration. The effectiveness of the controller is better for regular wavesthan for irregular waves and wind forces. Because the performance of the controller is unaf-fected by changes in the mass and stiffness of the TLP, the controller can be regarded asrobust.