Semi-active Control System Research Articles

Semi-Active Control Systems in Bridge Engineering: A Review of the Current State of Practice

In view of the grave socioeconomic consequences of earthquake damage to bridge structures, along with their critical role in modern and older road and rail networks, this article attempts to identify and summarise the current trends in the use of semi-active control technology in bridge engineering, as an enhanced seismic response control solution, combining increased adaptability and reliability, compared to passive and active schemes. In this context, representative analytical and experimental studies, as well as some full-scale applications of semi-active control devices are first reviewed and a brief description of relevant benchmark studies is subsequently presented, with a view to serving as a point of reference for further research and development. A framework of performance-based control principles aiming at the aforementioned objectives is finally set forth.

Optimal control of a plan asymmetric structure using magnetorheological dampers

Although building structures can be perceived as a combination of primary frames in two orthogonal directions, they are three-dimensional systems that usually present a very complex dynamic behavior due to irregular geometric configurations, in particular due to plant stiffness or mass eccentricities. This asymmetric geometry results in coupled lateral–torsional motion produced by wind and seismic loading with consequences in the design of lateral and corner columns. A considerable amount of research effort has been devoted to develop structural control systems to reduce the effects of plan asymmetries and to improve the dynamic behavior of these buildings. This paper presents a numerical analysis of a semi-active control system with MR dampers designed to reduce lateral–torsional responses of a plan asymmetric building structure excited by El Centro NS earthquake ground motion. A parametric study comprising passive and semi-active control modes is given to demonstrate the effectiveness of the proposed control system with respect to uncontrolled case. The numerical results prove the efficiency of the semi-active control system and its potential use in mitigating coupled lateral–torsional structural responses.

A Compact Autonomous Underwater Vehicle With Cephalopod-Inspired Propulsion

AbstractIn this paper, a bioinspired, compact, cost-effective autonomous underwater vehicle system is presented. Designed to operate in a heterogeneous, multivehicle collaboration hierarchy, the presented vehicle design features 3D printing technology to enable fast fabrication with a complex internal structure. Similar to a previous vehicle prototype, this system generates propulsive forces by expelling unsteady, pulsed jets, inspired by the locomotion of cephalopods and jellyfish. The novel thrusters enable the vehicle to be fully actuated in horizontal plane motions, without sacrificing the low-forward-drag, slender vehicle profile. By successively ingesting water and expelling finite water jets, periodic actuation forces are generated at all possible vehicle velocities, eliminating the need for control surfaces used in many conventional underwater vehicle designs. A semiactive buoyancy control system, inspired by the nautilus, adjusts the vehicle depth by passively allowing water flowing into and actively expelling water out of an internal bladder. A compact embedded system is developed to achieve the control and sensing capabilities necessary for multiagent interactions with the minimum required processing power and at a low energy cost. The new vehicle design also showcases an underwater optical communication system for short-range, high-speed data transmission, supplementing the conventional acoustic communication system. Experimental results show that, with the thruster motors powered at a 60% duty-cycle, the new vehicle is able to achieve a 1/4 zero-radius turn in 3.5 s and one-body-width sway translation in 2.5 s.

Decentralized Active Control of Multistory Civil Structure with Wireless Smart Sensor Nodes

AbstractWireless smart sensors, a popular option for structural health monitoring, are an exciting alternative to traditional tethered systems for structural control. Their onboard communication, sensing, actuation, and processing capabilities offer all the components for feedback control to limit structural response during earthquakes and wind. However, wireless smart sensors pose unique challenges for structural control including communication latency, delays, and data loss. Previous research in wireless structural control has used decentralized control approaches to overcome these inherent limitations. However, these experimental investigations have focused on semiactive control systems, in which stability is guaranteed. Thus, the semiactive wireless control implementations are less sensitive to delays and sampling rate limitations imposed by the smart sensors. This paper presents an experimental investigation of decentralized wireless active control. All the elements of the wireless control system are...

Semi-active control of flexible structures using closed-loop input shaping techniques

In this research effort, a novel approach on the control of structures with magnetorheological (MR) dampers is presented, based on an appropriately adapted closed-loop version of the generic input shaping control theory. The MR damper is a very promising kind of semi-active control system (actuator), mixing the advantages of the active and passive structural control systems, hence their increasing use as attenuators that reject the effects of dynamic loads on civil engineering structures. The main contribution of this article is the application and performance evaluation of the novel ‘Linear Matrix Inequality-based’ feedback version of the input shaping control theory for the first time in the area of structural control. The need for the use of a feedback version of input shaping control stems from the design trade-off between robustness and speed of response requirements. A simulation of a benchmark three-story building with one MR damper is employed to verify the efficiency of the proposed control approach. The nonlinear behaviour of the MR damper, rigidly connected between the first floor of the structure and the ground, is captured by the well-known Bouc–Wen model. The superiority and effectiveness of the proposed scheme in reducing the responses of the structure were proved using seven quantifiable evaluation criteria and by comparing these results with those achieved by classical and well-established alternative control schemes. Copyright © 2016 John Wiley & Sons, Ltd.

Development and Laboratory Confirmation of Innovative Self-Reliance Controller

Raising the structural seismic-resistant capability by ductility design and structural control to alleviate the structural response to earthquake are two main concepts of modern structural design. Ductile designed building is subjected to nonlinear status to dissipate energy, thus eliminating the crisis caused by resonance amplification effect. Although it can avoid much base shear and survive an earthquake without collapse, the tremendous structural deformation will lead to much structural damages. To improve such shortcomings by altering the dynamic characters of a structure, the structural response of building subject to strong earthquake needs to be minimized to ensure building within the elastic region. A novel self-reliance control technology combined with the hydraulic interface is proposed in this research. This technology will provide autonomous controls similar to those achieved by using a semi-active control system but without the use of electronic sensors and controllers. Three-stage experimental tests are planned to test and verify the energy-dissipation ratio of this technology, connected to hydraulic jack of hydraulic dampers with various conditions and subject to different external force with various amplitude and frequency. Test results exhibit that (1) this proposed technology may exhibit the hysteretic phenomenon but still show a certain energy-dissipating effectiveness without using computer, and the reliability for using the structural deformation as sensor and also performing continuous control of these proposed controllers has been confirmed in this research, (2) the input energy from the external forces can be converted to produce control actions of this proposed technology, (3) the energy-dissipating efficiency of this technology increases with higher vibration amplitude.

Optimal semi-active control of seismically excited MR-equipped nonlinear buildings using FLC and multi-objective NSGAII algorithms considering ground excitations

Among the variety of control algorithms, fuzzy logic control (FLC) strategies have the advantage of not depending on the system model behavior, of being simple, and intrinsically robust, and therefore they have recently been used to control the dynamic response of multi-story buildings equipped with semi-active supplemental damping devices. However, their tuning has shown to be a difficult task, especially when they use a multi-objective strategy. Introducing several FLC-based control strategies, an optimal semi-active control strategy using an advanced multi-objective optimization procedure called Non-dominated Sorting Genetic Algorithm II (NSGAII) has been proposed in this paper to mitigate the nonlinear structural response of a new generation of benchmark buildings. Besides peak inter-story drift ratio and peak floor acceleration, the base shear force as an extra objective has been used as the three-objective function for the multi-objective optimal design problem. The robustness of the optimized semi-active algorithms which were produced using binary tournament-based parents has been assessed for 3-story and 20-story nonlinear benchmark buildings experiencing nonlinear behavior during a wide range of earthquake records. The results showed that the performance of optimized semi-active control systems is acceptable and in some cases work much better than the non-optimized controllers taken in previous studies.

Experimental study on using electromagnetic devices on bridge stay cables for simultaneous energy harvesting and vibration damping

Flexible bridge stay cables are often vulnerable to problematic vibrations under dynamic excitations. However, from an energy perspective, such excessive vibrations denote a green and sustainable energy source to some electronic devices (such as semi-active dampers or wireless sensors) installed on the same cables. This paper presents an experimental study on a novel dual-function system called electromagnetic damper cum energy harvester (EMDEH). The proposed EMDEH, consisting of an electromagnetic device connected to an energy-harvesting circuit (EHC), simultaneously harvests cable vibration energy and provides sufficient damping to the cables. A fixed-duty-cycle buck–boost converter is employed as the EHC, which emulates a resistive load and provides approximately optimal damping and optimal energy harvesting efficiency when operating in discontinuous conduction mode. A 5.85 m long scaled stay cable installed with a prototype EMDEH is tested in the laboratory under a series of harmonic and random excitations. The EMDEH can achieve a control performance comparable to passive viscous dampers. An average electrical power of 31.6 and 21.51 mW is harvested under harmonic and random vibrations, respectively, corresponding to the efficiency of 16.9% and 13.8%, respectively. Moreover, this experimental study proves that optimal damping and energy harvesting can be achieved simultaneously, which answers a pending question regarding such a dual-objective optimization problem. Self-powered semi-active control systems or wireless sensor networks may be developed for bridge stay cables in the future based on the proposed concept in this study.

Modeling and analysis of a structure semi-active tuned liquid damper system

A tuned liquid damper (TLD), which is similar to a tuned mass damper (TMD), is a type of dynamic vibration absorber (DVA) that can be employed to reduce wind induced resonant vibrations of a structure. Improved TLD performance could be realized by equipping TLDs with variable energy dissipating capabilities such as damping screens, which can be adjusted through a certain mechanism, permitting optimal control performance to be maintained over a wide range of loading conditions in a semi-active mode of control. In this paper, a control strategy based on a gain scheduling scheme is utilized by controlling the inclination angle of the damping screen(s) and consequently the screen loss coefficient value(s). The gain scheduling control strategy is employed on a simple single-story structure equipped with a semi-active TLD (SA-TLD) in order to maintain the optimal damping value (ζTLD − opt) based on averaged or instantaneous structural response tracking and a prescribed look-up table. Results are assessed using experimental values from tests conducted on conventional passive TLDs. A performance comparison between a semi-active TLD control system and a conventional passive TLD control system is carried out. The fluid response amplitude for a SA-TLD is also investigated and compared to that of a passive TLD. Copyright © 2016 John Wiley & Sons, Ltd.

Posicast control of structures using MR dampers

Summary In this article, a novel application of a semi active posicast control scheme for structures with magneto-rheological (MR) dampers is presented. MR dampers are considered to be highly promising of semi-active control systems, which are becoming increasingly popular for alleviating the effects of dynamic loads on civil engineering structures because they combine the merits of both passive and active control systems. The main contribution of this article relates to the design, application, tuning and performance evaluation of the novel posicast control scheme for structural control. The efficiency of the suggested control strategy was evaluated by performing numerical simulations of a benchmark three-storey building with an MR damper, rigidly attached between the first floor and the ground. The damper's behaviour was simulated using the Bouc–Wen model. Seven evaluation criteria were used to assess the performance of the proposed posicast control scheme in reducing the excited structure's responses to dynamic loading. The simulation's results indicated that the posicast control scheme had significant advantages over conventional alternatives in terms of performance and efficiency. Copyright © 2016 John Wiley & Sons, Ltd.

LPV Control for a Semi-Active Suspension Quarter of Car-One Parameter Case

The actual semi-active suspension control systems with a balance between comfort and road holding goals are not optimal because in these solutions one goal or the other always dominates in the suspension performance. This paper is centered in a new proposal to control an automotive semi-active suspension to achieve the comfort and maintain the road holding.The output in the control strategy is the electric current. A nonlinear quarter of vehicle model simulation compares and validates the proposal versus different controllers. The controller is designed with the H∞ criteria and the Linear Varying Parameter (LPV) considering the saturation and sigmoid shape of the F-V characteristic diagram. Unlike the solutions in literature, which use at least two scheduling parameters, the proposed LPV controller scheme for a semi-active suspension uses only one scheduling parameter.

振動台を用いたセミアクティブ制御のリアルタイム・ハイブリッド実験

It's expected that near future's earthquake disasters are by huge pulse-type ground motions of an inland earthquake or long-period type ground motions of a subduction zone earthquake. Some concerns about seismic-isolated buildings can be also pointed out as follows: 1) Extra-large deformation of isolators exceeding the design criteria due to those types of earthquakes, 2) Degradation of seismic-isolated effects for reduction of acceleration response reduction due to the continuation of the long-time vibration. To overcome those problems, authors focus on introducing semi-active control systems on isolation layer. In this study, real time hybrid tests are performed on the mid-story isolated structures with semi-active device using the rotary inertia mass damper encapsulating magneto-rheological fluid (MR rotary inertia mass damper). In this test, isolation layer and superstructure are actually created as the test specimen, and lower part of structure is simulated by lumped mass system model in a computer. By using actual equipment of damper which has not been exactly clarified its behavior, modeling errors seem to be avoided, and the accuracy of the results on the hybrid test can be secured. This paper reports about constructing the system for real time hybrid test, and verifying its validity, moreover verifying the reproducibility of shaking table to confirm the reliability of this test. At first, mechanical specification of the experimental system and devices are evaluated. Steady vibration tests by sinusoidal waves are carried out on MR rotary inertia mass damper, and then its mechanical properties are modeled for numerical evaluations. The modeled formula is confirmed to agree to the experimental value, and is considered reasonable. A control time lag is observed when semi-active control is performed. This time lag is considered on the first-order delay system, and is also evaluated from experimental data. By considering this time lag effects on the numerical simulations, the precise experimental results can be gained. Lots of cases of the real time hybrid experiments for various types of earthquake input motions are operated. Those results are also compared with the numerical results by the fully modeled analyses, and the validity of the testing system, the modeling of this damper and the identification of the specimen are confirmed. Moreover, performance and the reproducibility of the real time simulators, which is actualized as the displacement of the shaking table, are evaluated. As results, high reproducibility of displacement of the shaking table by real time calculation could be observed and controlling errors could be manipulated to be negligible. At the same time, generated accelerations on the shaking table are observed performing accurately. However there is a little error in the reproduced acceleration for some cases. As a concluding remark, it is confirmed that reliable experimental system to operate real time hybrid test is constructed through this research.

Design, Analysis, and Experimental Evaluation of a Double Coil Magnetorheological Fluid Damper

A magnetorheological (MR) damper is one of the most advanced devices used in a semiactive control system to mitigate unwanted vibration because the damping force can be controlled by changing the viscosity of the internal magnetorheological (MR) fluids. This study proposes a typical double coil MR damper where the damping force and dynamic range were derived from a quasistatic model based on the Bingham model of MR fluid. A finite element model was built to study the performance of this double coil MR damper by investigating seven different piston configurations, including the numbers and shapes of their chamfered ends. The objective function of an optimization problem was proposed and then an optimization procedure was constructed using the ANSYS parametric design language (APDL) to obtain the optimal damping performance of a double coil MR damper. Furthermore, experimental tests were also carried out, and the effects of the same direction and reverse direction of the currents on the damping forces were also analyzed. The relevant results of this analysis can easily be extended to the design of other types of MR dampers.

Robust Vehicle Suspension System by Converting Active & Passive Control of a Vehicle to Semi-Active Control System Analytically

Robust Vehicle Suspension System by Converting Active & Passive Control of a Vehicle to Semi-Active Control System Analytically

A Study of the Dynamic Parameters Influence over the Behavior of the Two-Section Articulated Vehicle during the Lane Change Manoeuvre

Summary. The course stability and the steerability of the two-section wheeled vehicle at high velocities during the lane change manoeuvre are studied in this paper. Mechanicmathematical model is developed, on which base simulation programmes are elaborated. Simulation studies of the course stability at different velocities depend on some constructive and exploitation factors are made by these models. Based on the simulation results an idea for an algorithm and a semi-active control system of the resistance in the pulling-supporting device is proposed.

Semi-active control of seismic response of a building using MR fluid-based tuned mass damper

While tuned mass dampers are found to be effective in suppressing vibration in a tall building, integrating it with a semi-active control system enables it to perform more efficiently. In this paper a forty-story tall steel-frame building designed according to the Canadian standard, has been studied with and without semi-active and passive tuned mass dampers. The building is assumed to be located in the Vancouver, Canada. A magneto-rheological fluid based semi-active tuned mass damper has been optimally designed to suppress the vibration of the structure against seismic excitation, and an appropriate control procedure has been implemented to optimize the building's semi-active tuned mass system to reduce the seismic response. Furthermore, the control system parameters have been adjusted to yield the maximum reduction in the structural displacements at different floor levels. The response of the structure has been studied with a variety of ground motions with low, medium and high frequency contents to investigate the performance of the semi-active tuned mass damper in comparison to that of a passive tuned mass damper. It has been shown that the semi-active control system modifies structural response more effectively than the classic passive tuned mass damper in both mitigation of maximum displacement and reduction of the settling time of the building.

Semi-active fuzzy control of edgewise vibrations in wind turbine blades under extreme wind

In this paper, a new semi-active fuzzy control strategy is proposed for controlling edgewise vibrations of wind turbine blades under extreme wind. The control forces are provided by magnetorheological (MR) dampers mounted inside blades and appropriately manipulated according to a prescribed fuzzy control law. The fuzzy control system produces the required voltage to be input to the damper so that a desirable damper force can be produced. The finite element model of wind turbine with MR dampers is formulated, which considers the blade-tower coupling. Aerodynamic loads corresponding to a combination of steady wind and the effect of turbulence are computed by applying the blade element momentum (BEM) theory. Furthermore, the influence of position and number of the controllers is taken into account. The results of numerical simulations show that the proposed semi-active fuzzy control system can be beneficial in reducing the vibrations of wind turbine blades under extreme wind.

Semi-active vibration control of structural systems based on a reference active control law: output emulation approach

Summary A new semi-active control strategy that approximates a predicted control output of a reference active control is proposed. A variable parameter of a semi-active control device is selected at every time instant so that the predicted control output of the semi-active control system becomes close to the corresponding predicted control output of the reference active control as much as possible. Parameters of the reference active control law are optimized in the premise of the aforementioned ‘output emulation’ strategy so that the control performance of the semi-active control becomes good and the ‘error’ in the sense of achieved control performance between the reference active control and semi-active control systems becomes small. A pole placement method based on a linear matrix inequality (LMI) framework is adopted as the reference active control law. Parameters to determine the domain in the complex plane where the closed-loop poles are placed are searched so that control performance of the semi-active control system based on the output emulation approach is optimized. Copyright © 2015 John Wiley & Sons, Ltd.

Shaking table testing of a steel frame structure equipped with semi-active MR dampers: comparison of control algorithms

The effectiveness of the various control algorithms for semi-active structural control systems proposed in the literature is highly questionable when dealing with earthquake actions, which never reach a steady state. From this perspective, the paper summarizes the results of an experimental activity aimed to compare the effectiveness of four different semi-active control algorithms on a structural mock up representative of a class of structural systems particularly prone to seismic actions. The controlled structure is a near full scale 2-story steel frame, equipped with two semi-active bracing systems including two magnetorheological dampers designed and manufactured in Europe. A set of earthquake records has been applied at the base of the structure, by utilizing a shaking table facility. Experimental results are compared in terms of displacements, absolute accelerations and energy dissipation capability. A further analysis on the percentage incidence of undesired and/or unpredictable operations corresponding to each algorithm gives an insight on some factors affecting the reliability and, in turn, the real effectiveness of semi-active structural control systems.

Maximizing semi-active vibration isolation utilizing a magnetorheological damper with an inner bypass configuration

A single-degree-of-freedom (SDOF) semi-active vibration control system based on a magnetorheological (MR) damper with an inner bypass is investigated in this paper. The MR damper employing a pair of concentric tubes, between which the key structure, i.e., the inner bypass, is formed and MR fluids are energized, is designed to provide large dynamic range (i.e., ratio of field-on damping force to field-off damping force) and damping force range. The damping force performance of the MR damper is modeled using phenomenological model and verified by the experimental tests. In order to assess its feasibility and capability in vibration control systems, the mathematical model of a SDOF semi-active vibration control system based on the MR damper and skyhook control strategy is established. Using an MTS 244 hydraulic vibration exciter system and a dSPACE DS1103 real-time simulation system, experimental study for the SDOF semi-active vibration control system is also conducted. Simulation results are compared to experimental measurements.