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Summary: This paper presents a wavelet‐based strategy for fore‐aft vibration control of onshore horizontal axis wind turbine tower. For this purpose, an active tuned mass damper is combined with an aero‐servo‐elastic turbine model in the multi‐body framework. The combined system is exposed to turbulent wind and seismic ground motion to investigate the controller performance in extreme operating conditions. The optimal tuning is achieved by frequency‐dependent gain scheduling via wavelet transform. Analytic Morse wavelet is used as a basis function for transforming the input and feedback to recast the classical linear quadratic regulator (LQR) in the time‐frequency domain over a finite time horizon. The scale‐dependent differential Riccati equations are solved for optimal gains, which are used to estimate the optimal control force. Numerical studies presented in this paper demonstrate the advantage of the proposed gain scheduling over classical LQR. The efficiency of the proposed algorithm is verified using different flow conditions and seismic input, where the performance is compared with benchmark results. [ABSTRACT FROM AUTHOR]

Summary: Wireless sensor networks are becoming more popular for structural monitoring because of their low installation costs; in addition, coupling structural control with wireless data acquisition can also yield advantages. However, these systems have limited communication bandwidth, limiting their effectiveness as the number of devices in control networks grows large if centralized control approaches are used. Traditional methods for collocating data in wireless structural control network rely on time‐budgeted bandwidth or spatial decentralization, where the network is divided into smaller subnetworks. These methods are largely static and typically do not take into account any measure of data quality to prioritize transmissions. This study presents a dynamic approach for bandwidth allocation in wireless structural control networks that relies on an application‐specific, autonomous, and controller‐aware, carrier sense multiple access with collision detection protocol. Stochastic parameters are derived to strategically alter back‐off times in the carrier sense multiple access with collision detection algorithm based on nodal observability and output estimation error. Inspired by data fusion approaches, this paper presents 2 different methods for neighborhood state estimation using a dynamic form of measurement‐only fusion. Upon receiving data from the contended wireless medium, each wireless unit fuses incoming data using a precalculated static Kalman gain matrix for the corresponding dynamic neighborhood. Onboard, each wireless unit contains a library of Kalman gain matrices, to accommodate any possible set of communicated data. Both numerical simulations and small‐scale laboratory experimental results are presented. [ABSTRACT FROM AUTHOR]

As the number of sensors in a control network grows, it becomes increasingly difficult to transmit all sensor data during a single control step over the fixed wireless bandwidth. Because control force calculations rely on accurate state measurements or estimates, the use of staggered data communication may become necessary. It is not uncommon that a single sensor may be the only measurement source for an important section of a structure. This paper presents a means of selecting and evaluating different communication group sizes and wireless unit combinations for staggered communication that still provide information for highly accurate state estimates. Within each wireless unit, multiple estimator gains are stored on-board to perform state-estimation calculations using staggered data that may be received from different combinations of units. It is found that, in staggered communication schemes, state estimation and control performance are affected by the network topology used at each time step with some sensor combinations providing more useful information than others. Sensor placement theory is used to form sensor groups that provide consistently high-quality output information to the network over multiple time steps, so as to strategically report data from all sensors. [ABSTRACT FROM AUTHOR]

SUMMARY The optimization of tuned mass damper (TMD) involves the attachment of a damper to a TMD unit. Although this supplementary damping renders TMD to be operational under broad bandwidth inputs (i.e., wind excitation), it also considerably decreases the efficiency. In this paper, an alternative approach is suggested to eliminate the requirement for supplementary damping, hence to utilize TMD in full efficiency. For this purpose, combined structure/undamped TMD system is equipped with an active controller to track the response of an oscillator with natural frequency set to the operating frequency of the TMD unit. In this case, a proposed controller does not aim returning a system to its zero state; instead, it supports the TMD unit to suppress vibration effectively. This tracking type controller is formulized by both linear quadratic regulator, and H∞ control schemes, and control performances of each system are evaluated through numerical simulations. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]