Research On Event-triggered Sampled-data Control For Offshore Platforms

Offshore steel jacket platforms plays an increasingly important role in the exploration and utilization of marine resources.Located in the hostile ocean environments,the platform structures are inescapably subjected to external loads,which lead to nonlinear response of the offshore structures.To reduce the structural vibration and ensure the reliability,research on active control scheme has been extensively presented.Particularly,the sampled-data control method is also used to solve the vibration control problem of the offshore structure.To reduce the waste of network resources in traditional sampled-data control systems,the introduction of event-triggered mechanism is one of the effective control schemes.The event-triggered sampled-data control method of offshore platform is mainly considered in the paper.Details are as follows:Firstly,the event-triggered robust resilient control for offshore steel jacket structures is considered.For a class of offshore platform systems with an active tuned mass damper mechanism,an event-based data packet processor(DPP)is proposed to regulate the transmissions of the sampled-data on each sensor first of all.Since the packet transmission only occurs at the time instants when the event-based condition triggers,thus significantly reducing some unnecessary data transmissions and further saving precious communication resources.Second,by virtue of the time-delay system approach,the closed-loop system model of the offshore steel jacket structure is presented which considers the network-induced time delay and the nonlinearity and the uncertainty in offshore structure system as well as the control law gain perturbation.Then,by employing the Lyapunov-Krasovskii functional approach,sufficient conditions on the design of a desired resilient event-based controller are derived.Finally,the simulation results verify the effectiveness of the strategy.Secondly,the network-based modeling and event-triggered H_∞ control problems of offshore structure with active mass damper mechanism are considered.First of all,a network-based dynamic model of the offshore platform subject to external irregular wave force is presented.Second,an event-triggered mechanism is introduced to select the sampled-data packets that need to be transmitted through the networks during the control implementation.Then,based on the Lyapunov-Krasovskii functional method,the event-triggered H_∞ control problem for offshore platform is solved and the desired controller can be designed.Finally,it is demonstrated that from the simulation results the network-based controller can guarantee the performance of the offshore platform while saving precious communication resources.