Structure Control Technique Research Articles

A Review: Structural Shape and Stress Control Techniques and their Applications

AbstractThis review article presents prior studies on controlling shape and stress in flexible structures. The study offers a comprehensive survey of literature concerning the adjustment and regulation of shape, stress, or both in structures and emphasizes such control’s importance. The control of systems is classified into three primary classes: nodal movement control, axial force control, and controlling the two classes concurrently. Each class is thoroughly assessed, showcasing diverse methods anticipated by various scholars. Furthermore, the paper discusses methods to reduce the number of devices (actuators) to adjust and optimize actuators’ placement to achieve optimal structural control, considering the cost implications of numerous actuators. Additionally, various actuators are presented in detail, their advantages and disadvantages are also discussed. Moreover, the applications of the presented techniques are reviewed in detail, the essential recommendations for future work are also suggested.

Performance evaluation of iterative learning control with different sliding mode algorithms for the slip‐ratio control of an electric vehicle

AbstractDeveloping a control strategy that can handle model uncertainties, external disturbances, and parameter fluctuations is essential for the desired operation of a nonlinear system. An attempt is made to develop such a control algorithm using the Learning Variable Structure Control technique. The proposed controllers have the advantages of both iterative learning control (ILC) and sliding mode control (SMC) such that they can compensate both structured and unstructured uncertainties. They are made comprised of modified‐twisting algorithm and super‐twisting algorithm respectively with the ILC technique. In this article, the performance of the two developed controllers is compared to a traditional SMC‐based ILC approach. Based on simulation results, the super‐twisting algorithm based ILC is found to be superior with reference to speed of convergence and tracking accuracy. This method is used to control the slip‐ratio of an electric vehicle as a specific application in this paper.

Experimental model validation and predictive control strategy for an industrial fire-tube boiler

This paper presents a flexible control structure for fire-tube boilers based on a suitable integration of the typical decentralized PI control structure and model predictive control technique. First, a dynamic nonlinear reference model of the fire-tube boilers is developed combining models available in the technical literature, based on first principle laws. The overall system model is considered as a gray-box model, and it has been validated with real data. Then, a suitable control-oriented model is derived out of the nonlinear reference model, in order to design a hybrid cascade MPC-PI control structure capable of guaranteeing stability, improving performances and enforcing real-time constraints. The flexibility of such a structure can be exploited to impose different types of functional behavior to the boiler itself, from the performance-related ones to the efficiency increase ones. While the reference non-linear model is large and detailed, the control-oriented one is simplified so that a few process parameters are identified to reduce dramatically the implementation in the MPC controller hardware and software framework. A sensitivity analysis with respect to these process parameters highlights the robustness and easy implementation of such a strategy. Two MPC configurations have been developed and tested in simulation over the validated boiler model. Then, a customized algorithm has been developed to understand a massive quantization phenomenon on the boiler pressure measurement. Finally, a test session conducted on a real fire-tube boiler quantifies the performance benefits of one configuration of the MPC-PI control structure with respect to the PI control. • Tuning of a dynamic nonlinear reference model of the fire-tube boilers with real data. • A hybrid cascade MPC-decentralized PID control structure, easly tunable. • Sensitivity analysis to test the robustness and easy implementation of such a control strategy. • A customized algorithm to reject a massive quantization on the boiler pressure measurement. • Implementation of the optimal control strategy and test session on a real fire-tube boiler.

Adaptive variable structure observer for system states and disturbances estimation with application to building climate control system in a smart grid

In order to reach the ambitious net-zero emission target by 2050, various technological solutions need to be developed to ensure efficient utilisation of energy. Commercial and residential buildings are a big source of greenhouse gas emissions, where efficient utilisation of energy can play a major role towards decarbonisation of the buildings sector. Heat pumps have recently emerged as an effective solution for space heating applications in buildings. Energy-efficient operation of heat pumps will make a significant contribution toward making buildings energy-efficient. In this context, heat pump control systems have a major role. Some of the existing literature on the heat pump control systems assume that various system states are available to measure. This may not always be true and/or economical to measure all the states. Moreover, the system is subject to various disturbances which cannot be directly measured. To reduce the number of sensors in heat pump control systems, an adaptive observer is developed in this paper to estimate inaccessible system states and disturbances simultaneously. An advantage of the proposed approach is that it does not require any bound on the disturbance itself, however, only assumes that the rate of change of disturbance is bounded. This is always the case in practice. In the developed method, adaptive control techniques and variable structure control techniques are combined to implement the proposed observer. In order to estimate the unknown disturbance, an augmented systems model is considered. Globally uniformly ultimately bounded property of the error dynamical systems is established by suitably designing the adaptive laws. The developed method is applied to a model of the heat dynamics of a house floor heating system connected to a ground source-based heat pump. Different disturbance signals formats and amplitudes are considered to show the effectiveness of the proposed technique. Simulation results are given to demonstrate the suitability of the proposed method.

Bistable track nonlinear energy sinks with nonlinear viscous damping for impulsive and seismic control of frame structures

Engineering structures are susceptible to natural and man-made hazards, threatening structural normal functionality and safety. Considerable attention has been paid to the research and development of structural control techniques. Tuned mass dampers (TMDs) are control devices practically applied. However, they only exert the optimum control efficiency in the vicinity of the structural frequency. In contrast, nonlinear energy sinks (NESs) have recently proved robust against potential frequency changes in structures and external excitations, but their control effectiveness is dependent on input energy levels. To this end, a bistable track NES (BTNES) with nonlinear viscous damping is proposed in the present study. The track profile of BTNES is designed as a polynomial combining negative quadratic and positive quartic terms, which correspond to linearly negative stiffness and nonlinearly positive stiffness when an auxiliary mass moves on the curved track. The governing equations of a two-storey frame structure with BTNES subjected to impulsive loads are first derived. The track profiles and damping coefficients of BTNES are optimized for different viscous damping exponents. Then the control performances of BTNES are systematically investigated under various impulsive velocities, structural frequencies, and near-fault and far-field earthquake ground motions. The BTNES performances are also compared to those of a linear TMD and a traditional track NES with only a quartic profile. The results indicate that BTNES with a large viscous damping coefficient has superior control performances in terms of effectiveness, robustness, and damper stroke, which highlights that BTNES has promising applications in protecting structural safety against multiple dynamic hazards.

TMD stroke limiting influence on barge-type floating wind turbines

In this paper, passive structural control techniques are applied to a barge-type Floating Offshore Wind Turbine (FOWT) to mitigate the impact of pendulum effect loads. The passive structural control device, a tuned mass damper (TMD) installed in the nacelle, is analyzed on a reduced dynamics FOWT model. Genetic algorithms are used for the optimization process, taking the tower fatigue as the fitness function, implemented as the standard deviation of the fore-aft tower top displacement. The optimization of the TMD shows that its resulting stroke is unfeasible in terms of space needed for installation. Therefore, the addition of stroke-limiting stops to the TMD should be considered. A new optimization, including stops, yields a clear improvement of the device performance while limiting the stroke to the nacelle dimensions. It is observed that the stops allow to mitigate the second collective platform pitch-tower bending mode in addition to the first one. Finally, a third case is presented, considering the whole stops configuration as additional variables in the optimization loop. This last case improved the TMD performance in terms of vibration suppression rate, proving the effectiveness of optimizing stops for mass and space constrained applications.

Energy dissipation demand and distribution for multi-story buildings with fluid viscous dampers

The seismic response of structures with fluid viscous dampers (FVDs), which is a predominant type of structural control techniques, can be analysed from the perspective of energy. In such structures, the imposed seismic energy is mainly dissipated by the structural plastic energy, EP, and the energy dissipated by FVDs, Ed2, which quantify the structural cumulative damage and FVD’s seismic reduction effect, respectively. Research conducted in the past focuses on investigating the EP demand of systems without supplemental damping devices, but little knowledge is available for the EP and Ed2 demand in multi-story buildings equipped with FVDs. To fill this gap, this paper conducted a comprehensive investigation based on four steel-moment resisting buildings with different height (3-, 6-, 9-, and 20-stories, respectively) equipped with linear or nonlinear FVDs. The effect of structural property and FVDs properties, characterised by the supplemental damping ratio ξadd and velocity power α, on the EP and Ed2‘s overall demand and distributions among stories were illustrated. The results indicate coupling effects of structural property, ξadd and α, on the EP and Ed2 demands. In most cases, the increase of ξadd and the decrease of α can reduce the EP demand and increase the Ed2 response. However, the increasing of ξadd is not effective if it is larger than 20% and the FVDs with α = 0.3 are not recommended in relative high-rise buildings. The distribution pattern shows a trend of linearly decreasing along the height, but those in the high-rise buildings are disturbed by high-mode effects.

Load Reduction of Floating Wind Turbines Using Tuned Mass Dampers

Abstract: Offshore wind turbines have the potential to be an important part of the United States’ energy production profile in the coming years. In order to accomplish this wind integration, offshore wind turbines need to be made more reliable and cost efficient to be competitive with other sources of energy. To capitalize on high speed and highquality winds over deep water, floating platforms for offshore wind turbines have been developed, but they suffer from greatly increased loading. One method to reduce loadsin offshore wind turbines is the application of structural control techniques usuallyused in skyscrapers and bridges. Tuned mass dampers are one structural control system that have been used to reduce loads in simulations of offshore wind turbines. This thesis adds to the state of the art of offshore wind energy by developing a set of optimum passive tuned mass dampers for four offshore wind turbine platforms and byquantifying the effects of actuator dynamics on an active tuned mass damper design. The set of optimum tuned mass dampers are developed by creating a limited degree-of-freedom model for each of the four offshore wind platforms

Wind-Hess System with a Fuzzy base Control Method

The guideline objective of this article is a FUZZY situate Wind-Hess structure control technique to smother wind control change while contemplating the working area of HESS. This article has suggested a fleecy situate breeze HESS network control technique to smother wind control instability while considering the working states (SoC level) of HESS. The key motivation behind the controller is to dole out wind fluctuations with unmistakable repeat gatherings to the super capacitor and the battery by dynamically changing the time steady of primary and discretionary channel channels. The suitability of the suggested technique has been appeared for a watt power network. A feathery situate breeze HESS structure controller is suggested to smother the breeze control instabilities. The suggested controller abuses the complimentary traits of the super capacitor and battery with the super capacitor and battery responsible for high and focus repeat portions of wind changes, independently. In this endeavor PV structure is related with battery for better performance. The capability of the suggested arrangement in the article for wind.

Precise power descent control of a lunar lander using a single thruster

This paper addresses the problem of powered descent control of a lunar lander during its final landing phase, where soft and precise landing at the target cite is required. In the literature, this problem has been solved considering a fully actuated lunar lander. Recently, landers are designed as complex systems with several onboard payloads and subsystems for completing demanding mission tasks. There are increasing constraints on mass budget and space availability onboard a lander. In order to meet these requirements, a novel controller using a single thruster is proposed. The proposed controller has three control inputs (thrust and two gimbaled angles) to control the six degrees of motion of a lander; these control inputs are non-affine. The proposed controller is designed based on variable structure control technique augmented with a high order filter, an immersion and invariance-based mass estimator and a sliding mode angular velocity observer. The stability analysis using Lyapunov theory and the results of the numerical simulations along with Monte Carlo simulations of the system show that the precise landing of the lunar lander using a single thruster is feasible.

Response control of wind turbines with ungrounded tuned mass inerter system (TMIS) under wind loads

Wind turbine towers are sensitive to wind loads and lose efficiency when suffering excessive wind-induced vibrations. Structural control techniques such as tuned mass dampers (TMD) can be used to reduce the vibration response of the tower. However, the additional mass of this system would occupy a large amount of space within the wind turbine device, which can inconvenience installation and maintenance. An inerter is a high-efficiency two terminal mechanical element for vibration control with the characteristic of mass and damping enhancements. An ungrounded tuned mass inerter system (TMIS) –composed of a tuned mass, a tuned spring and an inerter subsystem – has potential to control wind-induced vibration efficiently. In this study, a simple design method for wind turbine towers equipped with a TMIS under wind loads is proposed, based on structural performance demand as well as control cost. A 1.5 MW wind turbine tower benchmark model is adopted to exemplify the proposed design method. Comparative analyses are conducted between a conventional TMD and the TMIS. Results show that the TMIS can achieve the same vibration control effect as the TMD while using a smaller tuned mass. A sensitivity study of the TMIS is also carried out to investigate the impact of mechanical element parameters on the performance of the vibration mitigation system. It is concluded that the optimal designed TMIS has the advantage of lightweight tuned mass over TMDs in wind-induce vibration control of wind turbine towers.

A Review of Piezoelectric Material-Based Structural Control and Health Monitoring Techniques for Engineering Structures: Challenges and Opportunities

With the breadth of applications and analysis performed over the last few decades, it would not be an exaggeration to call piezoelectric materials “the top of the crop” of smart materials. Piezoelectric materials have emerged as the most researched materials for practical applications among the numerous smart materials. They owe it to a few main reasons, including low cost, high bandwidth of service, availability in a variety of formats, and ease of handling and execution. Several authors have used piezoelectric materials as sensors and actuators to effectively control structural vibrations, noise, and active control, as well as for structural health monitoring, over the last three decades. These studies cover a wide range of engineering disciplines, from vast space systems to aerospace, automotive, civil, and biomedical engineering. Therefore, in this review, a study has been reported on piezoelectric materials and their advantages in engineering fields with fundamental modeling and applications. Next, the new approaches and hypotheses suggested by different scholars are also explored for control/repair methods and the structural health monitoring of engineering structures. Lastly, the challenges and opportunities has been discussed based on the exhaustive literature studies for future work. As a result, this review can serve as a guideline for the researchers who want to use piezoelectric materials for engineering structures.

Efficient direct displacement-based seismic design approach for structures with viscoelastic dampers

Viscoelastic damper (VED) is one of most effective structural control techniques, because it provides both additional stiffness and damping to the structures. Current seismic standards implement force-based methods for the design of VEDs, which generally require extensive iterative calculations. It also causes inconsistent risk degree and economic efficiency because it is displacements, rather than forces, that are directly related to structural damage. In the past decades, researchers have developed a direct displacement-based design (DDBD) methodology. The DDBD approach begins with selecting a target displacement and estimating of the equivalent damping ratio, and then calculate the seismic demand of the structure using a substitutive equivalent elastic system. However, because of the strong nonlinearity of the VED devices, it is difficult to appropriately proportion the key parameters (i.e., damping, period) of the VED controlled structure system, which makes the DDBD method ineffective. To solve this problem, this paper proposed an efficient DDBD approach that is in accordance with the Chinese seismic design principles. The relationship between the equivalent damping and structure period of the VED-structure system is established, so the proposed approach requires minimum iterative calculations and the efficiency improves significantly. A step-by-step description of the approach is presented, in which the two key VED parameters, namely the strain amplitude and its additional damping ratio contribution to the structure, are determined by the target displacements. The approach is further examined and verified by a 24 story building. Nonlinear history analysis results confirm that, by using the proposed DDBD procedure, the designed target story drift is achieved with no iterative calculations and the structural responses of the VED-structure system satisfy the code requirements.

Control of Full-Size Frame Structures via Optimum Tuned Mass Dampers

Structural control techniques are widely used to reduce the maximum values of the vibrations caused by strong earthquakes and winds and to rapidly dampen them. Among them, passive control systems have been used effectively to protect structural and non-structural elements from the destructive effects of earthquakes in the past quarter-century. Tuned mass dampers (TMD) that are part of passive control systems have been widely used in civil structures with their alternative benefits. In this study, the optimal adjustment of the parameters of a passive TMD placed on the top floor of the 10-story symmetrical structure was performed by a metaheuristic method called Jaya algorithm. The structural model was modeled in the SAP2000 finite element analysis software to obtain mass and stiffness properties. The results of the numerical analysis showed that the optimization of the TMD parameters is highly effective in reducing the total shear forces of the base of the full-size frame structures and reducing displacement in the event of seismic loads.

Parametric Study of Damping Characteristics of Magneto-Rheological Damper: Mathematical and Experimental Approach

The present research work is a part of a project was a semi-active structural control technique using magneto-rheological damper has to be performed. Magneto-rheological dampers are an innovative class of semi-active devices that mesh well with the demands and constraints of seismic applications; this includes having very low power requirements and adaptability. A small stroke magneto-rheological damper was mathematically simulated and experimentally tested. The damper was subjected to periodic excitations of different amplitudes and frequencies at varying voltage. The damper was mathematically modeled using parametric Modified Bouc-Wen model of magneto-rheological damper in MATLAB/SIMULINK and the parameters of the model were set as per the prototype available. The variation of mechanical properties of magneto-rheological damper like damping coefficient and damping force with a change in amplitude, frequency and voltage were experimentally verified on INSTRON 8800 testing machine. It was observed that damping force produced by the damper depended on the frequency as well, in addition to the input voltage and amplitude of the excitation. While the damping coefficient (c) is independent of the frequency of excitation it varies with the amplitude of excitation and input voltage. The variation of the damping coefficient with amplitude and input voltage is linear and quadratic respectively. More ever the mathematical model simulated in MATLAB was in agreement with the experimental results obtained.

Edgewise vibration suppression of multi-megawatt wind turbine blades using passive tuned mass dampers

The lack of aerodynamic damping of wind turbine blades in the edgewise direction causes larger dynamic responses and lowers the reliability. As blades become longer, edgewise fatigue loading increases rapidly. To mitigate the blade edgewise vibration, structural control techniques using a tuned mass damper (TMD) are applied in this paper. The “TMD” module in FASTv8 was upgraded to enable the high-fidelity simulation of structural control of the blade response. With the developed tool, the optimal parameters and generalized design formulas were established through a parametric study. Also, the control effect of the optimal blade-TMD on reducing fatigue and extreme loads of two different multi-megawatts turbine blades is investigated. Fully-coupled non-linear time marching simulations were conducted by running key design load cases (DLCs) with site-specific meteorological conditions. The results provide insight into the potential benefits and impacts of passive structural control to reduce the fatigue and extreme loads of turbine blades.

Neural Network-Based Adaptive Control for Spacecraft Under Actuator Failures and Input Saturations.

In this article, we develop attitude tracking control methods for spacecraft as rigid bodies against model uncertainties, external disturbances, subsystem faults/failures, and limited resources. A new intelligent control algorithm is proposed using approximations based on radial basis function neural networks (RBFNNs) and adopting the tunable parameter-based variable structure (TPVS) control techniques. By choosing different adaptation parameters elaborately, a series of control strategies are constructed to handle the challenging effects due to actuator faults/failures and input saturations. With the help of the Lyapunov theory, we show that our proposed methods guarantee both finite-time convergence and fault-tolerance capability of the closed-loop systems. Finally, benefits of the proposed control methods are illustrated through five numerical examples.

Conceptual design and dynamic analysis of a novel passive floating offshore wind turbine structure

ABSTRACT In order to mitigate dynamic responses of floating offshore wind turbines (FOWTs) under combined wind-wave-current loading, employment of structural control techniques is often considered. In this paper, a novel concept of a passive FOWT structure is proposed to overcome the previous limitations on space and mass of tuned mass dampers (TMDs). The conceptual design is examined on the basis of a finite element model. The dynamic responses, mainly roll and pitch rotations, are compared between the controlled and uncontrolled FOWTs. Subsequently, a parametric study is conducted and the main parameters in the model are optimised accordingly. Finally, the optimal performance of the proposed FOWT structure demonstrates the effectiveness of the proposed design, and also its superiority over the existing concepts.

Dynamic Response of Tall Building with Base Isolation Subjected to Earthquake Forces

In the fast-paced contemporary world, new inventions with rapid construction techniques came across usually built to resist the lateral forces. Among them, the demand for tall buildings has put a revolutionary impact on society. In this study, base isolation as an earthquake resisting design technique was utilized which substantially dissociate a superstructure from its substructure and increase flexibility resisting on the ground vibration areas by providing the different types of base isolators. Lead rubber bearing (LRB) isolator is a passive structural vibration control technique. In this research study, seismic behaviour of tube in tube system steel tall building in square, circular, hexagonal, and octagonal plan configurations with varying frame sections with and without LRB base isolation was analyzed for the comparative analysis on the basis of base shear, overturning moment, time period, storey displacement, storey drift and storey acceleration according to IS 1893 (part 1):2016 and UBC 1997 Earthquake code in E-TABS software by non-linear time history analysis. From the results, Octagonal shape was found to be the best option for tall buildings whereas the hexagonal shaped building showed poor performance during an earthquake.

Adaptive unit-vector law with time-varying gain for finite-time parameter estimation in LTI systems

A continuation of previous authors' work on adaptive parameter estimation for linear dynamical systems having irrational transfer function is presented in this work. An original modification of the gradient algorithm, inspired by the variable structure control techniques and additionally featuring a time-varying adaptation gain, is presented and analyzed using Lyapunov techniques. The exposition is illustrated by several numerical examples which illustrate the effectiveness of the proposed algorithm.