Marine structures are inevitably influenced by parametric perturbations as well as multiple external loadings. Among these loadings, earthquake is generally more destructive and unpredictable than others. It is significant to develop effective active control schemes to guarantee the safety, stability, and integrity of marine structures subject to earthquakes and parametric perturbations. In this paper, the problem of networked [Formula: see text] robust damping control is addressed to stabilize a marine structure subject to earthquakes. First, in consideration of perturbations of the structure parameters, an uncertain model of the networked marine structure under earthquakes is presented. Second, a robust networked [Formula: see text] control scheme is presented to suppress seismic responses of the structure. By using stability theory of time-delay systems, several sufficient conditions on robust stability of the networked marine structure system are obtained, and the linear matrix inequality methods are utilized to solve the gain matrix of the controller. Finally, simulation indicates that compared with the traditional robust [Formula: see text] control and the proposed networked [Formula: see text] control, the seismic responses amplitudes of the marine structure under the two controllers are almost the same, while the latter is more economic than the former.

目的:研究受非线性自激波浪力影响下的海洋平台网络化模糊系统建模和控制问题.方法:针对一类含有主动质量阻尼器的导管架海洋平台,采用Takagi-Sugeno(T-S)模糊方法模糊化平台振动模态固有频率建立海洋平台系统的模糊动力学模型;然后,通过构造Lyapunov-Krasovskii泛函并采用积分不等式方法研究海洋平台闭环系统的稳定性条件.结果:给出了海洋平台系统在网络控制环境下的T-S模糊动力学模型以及闭环系统渐近稳定的充分条件,从而提出了海洋平台网络化模糊控制器的设计方法.结论:仿真结果表明,本文提出的网络化模糊控制方法能够有效地降低平台的振动幅值,提高平台的安全性.

Vibration damping of jacket platforms is among the significant issues in marine science and engineering, and the design of active vibration control schemes is very important to ensure the stability and safety of the jacket platforms against external loadings. This paper provides three fuzzy output feedback H ∞ controllers of the jacket platforms for irregular wave forces. By considering time-varying masses of jacket platforms, a Takagi-Sugeno (T-S) fuzzy dynamic model of the structure is established. Then fuzzy output feedback H ∞ control schemes are developed via using output signals of the platform with current and/or are delayed. Several existence conditions of fuzzy output feedback H ∞ controllers are derived. Simulation results demonstrate that the fuzzy output feedback H ∞ control strategies are remarkable to suppress the vibration of structure. Moreover, by choosing proper delayed output information of the system, the presented delayed fuzzy output feedback H ∞ control schemes outperform the conventional fuzzy output feedback H ∞ control approach.

In this paper, fuzzy sliding mode control scheme is designed for offshore jacket stuctures with parameter perturbations and external waves. Firstly, the Takagi-Sugeno fuzzy model is proposed via considering the parameter perturbation of the system. Secondly, based on the state signals of the jacket stuctures with current and delayed states, a novel fuzzy sliding mode control method that is established from state signals of the system with current and delay to reduce oscillations of jacket stuctures. Thirdly, based on the obtained model, a sufficient condition for stability of offshore platfrom is derived via Lyapunov-Krasovskii functional approach. Finally, several simulation results show that the mixed delayed robust fuzzy sliding mode \(H_{\infty }\) control strategy can effectively stabilize offshore structures and make better performance of the controlled system.