Wind turbines controllers design based on the super-twisting algorithm

The continuous increase in the size of wind turbines (WTs) has led to new challenges in the design of novel torque and pitch controllers. Today’s WT control design must fulfill numerous specifications to assure effective electrical energy production and to hold the tower vibrations inside acceptable levels of operation. Hence, this paper presents modern torque and pitch control developments based on the super-twisting algorithm (STA) by using feedback of the fore- aft and side-to-side acceleration signals of the WT tower. According to numerical experiments realized using FAST, these controllers mitigate vibrations in the tower without affecting the quality of electrical power production. Moreover, the proposed controllers’ performance is better than the baseline controllers used for comparison.Postprint (author's final draft

A novel iterative linear matrix inequality design procedure for passive inter-substructure vibration control

In vibration control of compound structures, inter-substructure damper (ISSD) systems exploit the out-of-phase response of different substructures to dissipate the kinetic vibrational energy by means of inter-substructure damping links. For seismic protection of multistory buildings, distributed sets of interstory fluid viscous dampers (FVDs) are ISSD systems of particular interest. The connections between distributed FVD systems and decentralized static output-feedback control allow using advanced controller-design methodologies to obtain passive ISSD systems with high-performance characteristics. A major issue of that approach is the computational dificulties associated to the numerical solution of optimization problems with structured bilinear matrix inequality constraints. In this work, we present a novel iterative linear matrix inequality procedure that can be applied to obtain enhanced suboptimal solutions for that kind of optimization problems. To demonstrate the effectiveness of the proposed methodology, we design a system of supplementary interstory FVDs for the seismic protection of a five-story building by synthesizing a decentralized static velocity-feedback H∞ controller. In the performance assessment, we compare the frequency-domain and time-domain responses of the designed FVD system with the behavior of the optimal static state-feedback H∞ controller. The obtained results indicate that the proposed approach allows designing passive ISSD systems that are capable to match the level of performance attained by optimal state-feedback active controllers.This research was partially supported by the Spanish Ministry of Economy and Competitiveness under Grant DPI2015-64170-R/FEDER and by the Italian Ministry of Education, University and Research under the Project “Department of Excellence LIS4.0—Lightweight and Smart Structures for Industry 4.0”Peer ReviewedPostprint (published version

Integrated design of hybrid interstory-interbuilding multi-actuation schemes for vibration control of adjacent buildings under seismic excitations

The design of vibration control systems for the seismic protection of closely adjacent buildings is a complex and challenging problem. In this paper, we consider distributed multi-actuation schemes that combine interbuilding linking elements and interstory actuation devices. Using an advanced static output-feedback H∞ approach, active and passive vibration control systems are designed for a multi-story two-building structure equipped with a selected set of linked and unlinked actuation schemes. To validate the effectiveness of the obtained controllers, the corresponding frequency responses are investigated and a proper set of numerical simulations is conducted using the full scale North–South El Centro 1940 seismic record as ground acceleration disturbance. The observed results indicate that using combined interstory-interbuilding multi-actuation schemes is an effective means of mitigating the vibrational response of the individual buildings and, simultaneously, reducing the risk of interbuilding pounding. These results also point out that passive control systems with high-performance characteristics can be designed using damping elements.Peer ReviewedPostprint (published version

Application of Tuned Mass Dampers for Structural Vibration Control: A State-of-the-art Review

Given the burgeoning demand for construction of structures and high-rise buildings, controlling the structural vibrations under earthquake and other external dynamic forces seems more important than ever. Vibration control devices can be classified into passive, active and hybrid control systems. The technologies commonly adopted to control vibration, reduce damage, and generally improve the structural performance, include, but not limited to, damping, vibration isolation, control of excitation forces, vibration absorber. Tuned Mass Dampers (TMDs) have become a popular tool for protecting structures from unpredictable vibrations because of their relatively simple principles, their relatively easy performance optimization as shown in numerous recent successful applications. This paper presents a critical review of active, passive, semi-active and hybrid control systems of TMD used for preserving structures against forces induced by earthquake or wind, and provides a comparison of their efficiency, and comparative advantages and disadvantages. Despite the importance and recent advancement in this field, previous review studies have only focused on either passive or active TMDs. Hence this review covers the theoretical background of all types of TMDs and discusses the structural, analytical, practical differences and the economic aspects of their application in structural control. Moreover, this study identifies and highlights a range of knowledge gaps in the existing studies within this area of research. Among these research gaps, we identified that the current practices in determining the principle natural frequency of TMDs needs improvement. Furthermore, there is an increasing need for more complex methods of analysis for both TMD and structures that consider their nonlinear behavior as this can significantly improve the prediction of structural response and in turn, the optimization of TMDs

Design of distributed multi-actuator systems with incomplete state information for vibration control of large structures

In this paper, we investigate the design and performance of static feedback controllers with partial-state information for the seismic protection of tall buildings equipped with incomplete multi-actuation systems. The proposed approach considers a partially instrumented multi-story building with an incomplete system of interstory force–actuation devices implemented on selected levels of the building, and an associated set of collocated sensors that measure the corresponding interstory drifts and interstory velocities. The main elements of the proposed controller design methodology are presented by means of a twenty-story building equipped with a system of ten interstory actuators arranged in three different layouts: concentrated, semi-distributed and fully-distributed. For these control configurations, partial-state controllers are designed following a static output-feedback H-infinity controller design approach, and the corresponding frequency and time responses are investigated. The obtained results clearly indicate that the proposed partial-state controllers are effective in mitigating the building seismic response. They also show that a suitable distribution of the instrumented stories is a relevant factor in the control system performance.Peer ReviewedPostprint (published version

RESEARCH TOWARDS THE DESIGN OF A NOVEL SMART FLUID DAMPER USING A MCKIBBEN ACTUATOR

Vibration reducing performance of many mechanical systems, decreasing the quality of manufactured products, producing noise, generating fatigue in mechanical components, and producing an uncomfortable environment for human bodies. Vibration control is categorized as: active, passive, or semi-active, based on the power consumption of the control system and feedback or feed forward based on whether sensing is used to control vibration. Semi-active vibration control is the most attractive method; one method of semi-active vibration control could be designed by using smart fluid. Smart fluids are able to modify their effective viscosity in response to an external stimulus such as a magnetic field. This unique characteristic can be utilised to build semi-active dampers for a wide variety of vibration control systems. Previous work has studied the application of smart fluids in semi-active dampers, where the kinetic energy of a vibrating structure can be dissipated in a controllable fashion. A McKibben actuator is a device that consists of a rubber tube surrounded by braided fibre material. It has different advantages over a piston/cylinder actuator such as: a high power to weight ratio, low weight and less cost. Recently McKibben actuator has appeared in some semi-active vibration control devise. This report investigates the possibility of designing a Magnetorheological MR damper that seeks to reduce the friction in the device by integrating it with a McKibben actuator. In this thesis the concept of both smart fluid and McKibben actuator have been reviewed in depth, and methods of modelling and previous applications of devices made using these materials are also presented. The experimental part of the research includes: designing and modelling a McKibben actuator (using water) under static loads, and validating the model experimentally. The research ends by presenting conclusions and future work

Semi-active control of an integrated full-car suspension with seat suspension and driver body model using ER dampers

In this paper, an integrated vehicle semi-active suspension control system that includes a full-car suspension model (7 Degree-Of-Freedom (DOF)), a seat suspension model (2 DOF) and a driver body model (4 DOF) is developed. A H∞ static output feedback controller which only uses measurable variables as feedback signals is designed to improve vehicle ride comfort performance in terms of driver head acceleration under constraints of actuator saturation, suspension deflection limitation and road holding capability. The controller design conditions, which are expressed as Linear Matrix Inequalities (LMIs) are derived by dealing with each control input separately under a common Lyapunov function, so that a feasible solution can be found for the integrated high order system that has five control inputs and ten control outputs; each control input may require different feedback signals and have different saturation limitations. Furthermore, a semiactive control strategy is applied to implement the proposed control system using electrorheological (ER) dampers. Numerical simulations are used to evaluate theimprovement of ride comfort performance in terms of driver head acceleration responses under typical road disturbances

Comfort based floor design employing tuned inerter mass system

A comfort-based optimal method has been developed for designing floors using tuned inerter mass systems (TIMS) to reduce the vertical-vibration response of floors subjected to human-induced excitations. Acceleration response of the floor and output force of TIMS were first derived via stochastic analysis. Subsequently, variation patterns in acceleration-response and output-force ratios were studied and compared by changing values of TIMS parameters. Based on the results of this parametric investigation, a comfort-based optimal design method and the corresponding procedure to be followed were developed. In the proposed method, the weighted average of the required additional tuned mass and TIMS output force are expected to be minimized whilst realizing the expected level of satisfaction in terms of target comfort performance of the floor structure (i.e., target acceleration response ratio). For different design targets, optimized TIMS parameters can be obtained using the proposed design method, and such design cases have been demonstrated by performing time-history analysis under different external human-induced excitations. Results of the said analysis demonstrate that the proposed design method effectively satisfies comfort-performance objectives of a floor with optimal actual mass through use of an inerter system. In addition, the proposed method can be used to maintain a balance between the control cost, additional tuned mass, and structural comfort performance

Data Mining Technology for Structural Control Systems: Concept, Development, and Comparison

Structural control systems are classified into four categories, that is, passive, active, semi-active, and hybrid systems. These systems must be designed in the best way to control harmonic motions imposed to structures. Therefore, a precise powerful computer-based technology is required to increase the damping characteristics of structures. In this direction, data mining has provided numerous solutions to structural damped system problems as an all-inclusive technology due to its computational ability. This chapter provides a broad, yet in-depth, overview in data mining including knowledge view (i.e., concept, functions, and techniques) as well as application view in damped systems, shock absorbers, and harmonic oscillators. To aid the aim, various data mining techniques are classified in three groups, that is, classification-, prediction-, and optimization-based data mining methods, in order to present the development of this technology. According to this categorization, the applications of statistical, machine learning, and artificial intelligence techniques with respect to vibration control system research area are compared. Then, some related examples are detailed in order to indicate the efficiency of data mining algorithms. Last but not least, capabilities and limitations of the most applicable data mining-based methods in structural control systems are presented. To the best of our knowledge, the current research is the first attempt to illustrate the data mining applications in this domain