Robust mixed \[H_2 /H_\infty \] active control for offshore steel jacket platform

• Published in: Nonlinear dynamics Vol. 78; no. 2; pp. 1503 - 1514
• Main Author: Yang, Jia Sheng
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01.10.2014
• Subjects: Active control; Constraints; Control methods; Control systems design; Control theory; Dynamics; Linear matrix inequalities; Mathematical analysis; Matrix methods; Nonlinear dynamics; Offshore drilling rigs; Offshore engineering; Offshore platforms; Offshore structures; Random waves; Upper bounds; Vibration; Wave excitation
• ISSN: 0924-090X; 1573-269X
• DOI: 10.1007/s11071-014-1531-x

This paper presents a robust mixed \[H_2 /H_\infty \] control method for wave-excited offshore jacket platforms. Its objective was to design a controller that minimizes the upper bound of the \[H_2 \] performance measure on platform dynamics satisfying some \[H_\infty \] norm bound constraint simultaneously. Based on mixed \[H_2 /H_\infty \] control theory and linear matrix inequality techniques, a novel approach to stabilize offshore platform vibration with constrained \[H_2 /H_\infty \] performances is proposed. Uncertainties of the wave excitation are considered in dynamic performance analysis of offshore platforms. A reduced mode offshore platform structure under wave excitation is analyzed, and simulations are used to verify the effectiveness of the proposed approach. Compared with existing \[H_\infty \] control methods, the proposed approach makes a significant improvement for dynamic performances of offshore platforms under random wave excitation.