Semi-active Devices Research Articles

Novel design of a self powered and self sensing magneto-rheological damper

Magneto-rheological (MR) dampers are semi-active control devices and use MR fluids. Magneto-rheological dampers have successful applications in mechatronics engineering, civil engineering and numerous areas of engineering. At present, traditional MR damper systems, require a isolated power supply and dynamic sensor. This paper presents the achievability and accuracy of a self- powered and self-sensing magneto-rheological damper using harvested energy from the vibration and shock environment in which it is deployed and another important part of this paper is the increased yield stress of the Magneto rheological Fluids. Magneto rheological fluids using replacement of glass beads for Magnetic Particles to surge yield stress is implemented here. Clearly this shows better result on yield stress, viscosity, and settling rate. Also permanent magnet generator (PMG) is designed and attached to a MR damper. For evaluating the self-powered MR damper's vibration mitigating capacity, an Engine Mount System using the MR damper is simulated. The ideal stiffness of the PMG for the Engine Mount System (EMS) is calculated by numerical study. The vibration mitigating performance of the EMS employing the self-powered & self sensing MR damper is theoretically calculated and evaluated in the frequency domain.

Determining the physical limits on semi-active control performance: a tutorial

SUMMARY Control forces in semi-active control systems are constrained by the dynamics of actuators that regulate energy transmission through variable damping and/or stiffness mechanisms. The potential benefit of the development and implementation of new semi-active control devices and applications can be determined by optimizing the controlled performance subject to the constraints of the dynamics of the system being controlled (given by the state equations), the constraints associated with the dynamics of the semi-active device, and the expected external forcing. Performance optimization of semi-active control systems is a constrained two-point boundary value problem. This paper shows how this constrained problem can be transformed into an unconstrained problem, and how to easily solve the related unconstrained problem with Matlab. The method is illustrated on the performance optimization of a simple semi-active tuned-mass-damper for a structure subjected to ground accelerations. Several possible extensions of this method and application are offered. Copyright © 2013 John Wiley & Sons, Ltd.

Semi-active Control of Building Structures using Variable Stiffness Device and Fuzzy Logic

Semi-active control devices, also called “Intelligent” control devices, constitute the positive aspects of both the passive and active control devices. A semi-active control strategy is similar to the active control strategy, but this control device has been shown to be more energy-efficient than active devices. A particular type of semi-active control device, the Variable Stiffness Device (VSD), consists of a hydraulic cylinder with a normally closed solenoid control valve inserted in the tube connecting the two cylinder chambers. This paper emphasizes on the application of Semi-active Fuzzy Logic Controller (SFLC) of this system for getting the best results in the reduction of the building responses under earthquake excitations. For the numerical example, a 12-story building, located in the city of Rasht, Iran, is modeled as 3-D frame and the problem is solved in state space. The results obtained from the proposed control scheme (SFLC) are compared with those obtained from the ON-OFF control method. It is found that the SFLC is highly effective in reducing the responses of the example building than the ON-OFF algorithm. In this study, the optimal values of the fuzzy rule bases, membership functions, and the location of the control device are determined.

Heat Transfer Efficiency of Aluminum Substrates With Embedded Semi-Active Thermal Control Device

This article presents the work carried out in evaluating the efficiency of embedded heat pipes in simulated satellite substrates subjected to localized heat sources. The experimental setup that comprises either an aluminum plate or an aluminum honeycomb sandwich panel with an electrical heating element was designed. Various experiments were conducted on the substrates with and without embedded heat pipes at various heating power inputs. Case studies with adjoined and inclined substrates, employing either one or two embedded heat pipes having different insertion lengths, were performed. With the help of COMSOL Multiphysics 3.5a software, an equivalent three-dimensional finite-element model of the experimental setup was created and analyzed under the same real-time conditions. Based on the experimental results, design guidelines are proposed for optimized heat management within a satellite substrate using embedded heat pipes.

Numerical Modeling of New Semiactive Damper Actuator

AbstractRecent investigations have demonstrated the ability of semiactive devices to reduce the structural vibration. In this paper, a new device called the semiactive damper actuator (SADA) is introduced, which reduces the vibration response of structures during earthquakes. Numerical simulations are carried out to study the effects and advantages of SADA. Simulation results are presented and the responses of structures equipped with this device are compared with ones equipped with other similar devices. The results show SADA’s ability to reduce the seismic response of structures. SADA is a semiactive type and requires low energy to operate; therefore, it can be used widely to control the seismic response of structures.

The Analysis for Semi-Active Control Application in the MSCSS Subjected to Seismic Excitation

This Paper focuses on the semi-active control application in the Mega-Sub Controlled Structure System (MSCSS) subjected to seismic excitation. The semi-active control devices, which are installed in the MSCSS between the mega-structure and sub-structure, were designed by using fuzzy neural network, and those semi-active control rules were optimized to enhance the control efficiency by using the genetic algorithm. A semi-active control problem of the MSCSS subjected to seismic excitation was investigated, the time history analyses under different seismic excitation, which like El Centro seismic wave and Taft seismic wave, were performed by using MATLAB. The calculation results demonstrate that the semi-active control combining the fuzzy neural network and genetic algorithm can clearly enhances the seismic performance of the MSCSS and it also provides an improved reduction in the dynamic response when compared to the passive control scheme.

Design of magnetorheological damper with a combination of shear and squeeze modes

Magnetorheological (MR) damper is a semi-active suspension device that uses MR fluid to produce controllable damper. The mechanical properties of the suspension can be controlled by adjusting the yield stress of MR fluid. This paper presents the design of a new concept for MR damper with a combination of shear and squeeze working modes. Finite Element Method Magnetics (FEMM) was utilized to simulate the magnetic field generated by electromagnetic coils in MR damper. The MR damper was designed and fabricated according to the simulation results. The experimental tests were performed under quasi-static loading in three different conditions; shear mode, squeeze mode and combination of both modes. The results showed that the mixed mode MR damper has produced a unique damping characteristic where in general, a higher damping force has obtained in mixed mode than single mode.

Modeling and analysis of magnetorheological inner mass single unit impact dampers

In this article, ongoing studies to apply semi-active control devices to reduce undesired vibrations of civil engineering structures are investigated. In doing so, the barrier of the nonlinear inner mass single unit impact dampers is equipped by the magnetorheological fluid dampers. For convenience, this kind of impact dampers is briefly named smart impact dampers. Dynamic behavior of a vibratory system equipped with the smart impact damper is modeled based on the modified Bouc–Wen model for the magnetorheological damper. Performance of the smart impact damper to suppress free vibration of an Euler–Bernoulli beam is investigated. Furthermore, effects of varying applied current to the magnetorheological fluid damper on vibratory behavior of the beam are illustrated in user-oriented charts. The analysis results show that the smart impact dampers with optimal parameters can suppress undesired vibrations much better than conventional impact damper systems.

Hybrid system identification for high-performance structural control

Structural systems installed with active or semi-active control devices usually require availability of a high-fidelity model to determine appropriate control designs. Use of traditional system identification techniques has proven to be challenging, primarily due to the fact that such models must be multiple-input and multiple-output (MIMO) systems; the inputs correspond to the excitation and the control commands, while the outputs correspond to the measured responses. Even if a model is identified that can represent well the response of the structure, this model is often a non-minimal realization (i.e., the dynamics of various modes are duplicated in the model); these extra dynamics can degrade the performance of the resulting controller. This paper presents a hybrid system identification approach that can result in minimal (or near-minimal) realizations of the MIMO structure–control system models that are effective for structural control design. The first step in this approach develops a simplified model which can portray adequately the system characteristics found in the experimental data. Using information about the pole–zero relationship of the transfer function in the simplified model, a frequency-domain system identification strategy is employed subsequently to derive multiple single-input and multiple-output (SIMO) models with respect to each system input. The systems are then combined to determine the complete MIMO system model that is accurate over the frequency range of interest for the control applications. To demonstrate this hybrid approach, an example is provided to illustrate a high-fidelity identification result from the experiment of an actively isolated building system. Successful control implementation demonstrates the efficacy of this hybrid system identification approach.Structural systems installed with active or semi-active control devices usually require availability of a high-fidelity model to determine appropriate control designs. Use of traditional system identification techniques has proven to be challenging, primarily due to the fact that such models must be multiple-input and multiple-output (MIMO) systems; the inputs correspond to the excitation and the control commands, while the outputs correspond to the measured responses. Even if a model is identified that can represent well the response of the structure, this model is often a non-minimal realization (i.e., the dynamics of various modes are duplicated in the model); these extra dynamics can degrade the performance of the resulting controller. This paper presents a hybrid system identification approach that can result in minimal (or near-minimal) realizations of the MIMO structure–control system models that are effective for structural control design. The first step in this approach develops a simplified model which can portray adequately the system characteristics found in the experimental data. Using information about the pole–zero relationship of the transfer function in the simplified model, a frequency-domain system identification strategy is employed subsequently to derive multiple single-input and multiple-output (SIMO) models with respect to each system input. The systems are then combined to determine the complete MIMO system model that is accurate over the frequency range of interest for the control applications. To demonstrate this hybrid approach, an example is provided to illustrate a high-fidelity identification result from the experiment of an actively isolated building system. Successful control implementation demonstrates the efficacy of this hybrid system identification approach.

Effectiveness analysis of a semiactive base isolation strategy using information from an early-warning network

In this paper the possibility to manage data transferred by a Seismic Early Warning network to protect from collapse Base Isolated strategic structural systems by using semiactive devices has been investigated. In particular, by estimating the frequency content of the incoming seismic signal recorded at the accelerometric stations using a Fast Fourier Transform (FFT) technique, a new approach is proposed to estimate the seismic demand of the structure to be protected in order to eventually modify its mechanical features by means of semiactive devices. The analysis concerns a Base Isolated benchmark system equipped with semiactive devices located at the isolation layer, capable of modifying both the stiffness and damping of the overall structural system.The effectiveness of the proposed strategy has been tested on varying the “anticipation time”, namely the range of the time interval between the start of the seismic data elaboration by the recorded stations and the arrival of the seismic S-wave to the interested site, the added stiffness and damping resources, as well as by taking into account different seismic input signals.The results highlight the practical feasibility of the proposed strategy as well as the critical role played by the considered parameters on the performance of both the isolation level and superstructure. This work has to be intended as a first contribution concerning the potentiality of the Early Warning applications in reducing the seismic risk in built environments.

Lifetime Extension of a Realistic Model of an In-Service Bridge through a Response Modification Approach

Many highway bridges in the United States are reaching their intended design lives and are in need of attention. To avoid replacing these bridges simultaneously, methodologies to safely extend their lives are important to help avoid high replacement costs and to allow for bridge replacement to occur over a longer time window. This paper expands an approach to extend the fatigue life of vulnerable steel bridges through a response modification (RM) apparatus, consisting of a mechanical amplifier and a RM device, which provide efficient supplemental stiffness and damping to the bridge. Because of the relatively small deflections encountered under typical service loads, the use of a mechanical amplifier allows for a more efficient and less intrusive apparatus to provide the required RM forces imparted to the bridge for increased bridge life. This paper presents a parameter study exploring the flexibility of the elements in the RM apparatus, the length of the apparatus, and the characteristics of the RM device. The analyses also add superstructure damping and other model improvements to a comprehensive numerical model of a realistic in-service bridge. The paper carries out dynamic analyses in the frequency domain to ensure the robustness of the RM apparatuses for various loading frequencies. The most important characteristic of the RM apparatus is found to be the cross-sectional area of the members. Additionally, the parameter study showed that a smaller apparatus is most cost effective. Finally, the dynamic analyses showed that the use of a semiactive device may be beneficial to the effectiveness of the RM approach.

Over-driven control for large-scale MR dampers

As semi-active electro-mechanical control devices increase in scale for use in real-world civil engineering applications, their dynamics become increasingly complicated. Control designs that are able to take these characteristics into account will be more effective in achieving good performance. Large-scale magnetorheological (MR) dampers exhibit a significant time lag in their force–response to voltage inputs, reducing the efficacy of typical controllers designed for smaller scale devices where the lag is negligible. A new control algorithm is presented for large-scale MR devices that uses over-driving and back-driving of the commands to overcome the challenges associated with the dynamics of these large-scale MR dampers. An illustrative numerical example is considered to demonstrate the controller performance. Via simulations of the structure using several seismic ground motions, the merits of the proposed control strategy to achieve reductions in various response parameters are examined and compared against several accepted control algorithms. Experimental evidence is provided to validate the improved capabilities of the proposed controller in achieving the desired control force levels. Through real-time hybrid simulation (RTHS), the proposed controllers are also examined and experimentally evaluated in terms of their efficacy and robust performance. The results demonstrate that the proposed control strategy has superior performance over typical control algorithms when paired with a large-scale MR damper, and is robust for structural control applications.

MR- and ER-Based Semiactive Engine Mounts: A Review

Hybrid propulsion technologies, including hybrid electric and hydraulic hybrid, equip vehicles with nonconventional power sources (in addition to the internal combustion engine) to provide higher fuel efficiency. However, these technologies tend to lead to higher levels of noise, vibration, and harshness in the vehicles, mainly due to the switching between the multiple power sources involved. In addition, the shocks and vibrations associated with the power sources switching may occur over a wide range of frequencies. It has been proven that passive vibration isolators (e.g., elastomeric and hydraulic mounts) are unable to mitigate or totally isolate such shocks and vibrations. Active mounts, while effective, are more complex, require significant power to operate, and can lead to system instabilities. Semiactive vibration isolators have been shown to be as effective as active mounts while being less complex and requiring less power to operate. This paper presents a review of novel semiactive shock and vibration isolators developed using magnetorheological and electrorheological fluids. These fluids change their yield stress in response to an externally applied magnetic and electric field, respectively. As a result, these fluids allow one to transform a passive hydraulic vibration isolator into a semiactive device.

Technologies for Powered Ankle-Foot Orthotic Systems: Possibilities and Challenges

Ankle-foot orthoses (AFOs) can be used to ameliorate the impact of impairments to the lower limb neuromuscular motor system that affect gait. Existing AFO technologies include passive devices with fixed and articulated joints, semiactive devices that modulate damping at the joint, and active devices that make use of a variety of technologies to produce power to move the foot. Emerging technologies provide a vision for fully powered, untethered AFOs. However, the stringent design requirements of light weight, small size, high efficiency, and low noise present significant engineering challenges before such devices will be realized. Once such devices appear, they will present new opportunities for clinical treatment of gait abnormalities.

Dynamic response time of a metal foam magneto-rheological damper

Magneto-rheological (MR) dampers are a promising type of semi-active control device for various dynamic systems. Recently, low-cost MR dampers without any sealing structure have been required. Motivated by the desire to overcome the need for the costly dynamic seals of conventional MR dampers, a new type of metal foam MR damper is proposed in this study and the dynamic response performance is also investigated. The metal foam is firmly adhered to a working cylinder to store the unexcited MR fluids. In the action of a magnetic field, MR fluids will be extracted from the metal foam and fill up the shear gap to produce the MR effect. Three time parameters related to response time are introduced to further describe the dynamic response process. The results show that, due to the period required for extracting the MR fluids out from the metal foam, the time to produce the damper force of the metal foam MR damper is longer than for conventional fluid-filled MR dampers. The response time of the metal foam MR damper will change with different currents and shear rates. Given a constant shear rate, in a small range of currents (0–1.5 A), the response time decreases rapidly as the operating current increases; however, there is a slower change rate in larger ranges. To evaluate the effect of shear rate on response time, shear rates ranging from 2 to 10 s−1 are tested, and the results demonstrate that with increasing shear rates the response time decreases.

Response of a quarter car model with optimal magnetorheological damper parameters

In this paper, the control of the stationary response of a quarter car model to random road excitation with a Magnetorheological (MR) damper as a semi-active suspension device is considered. The MR damper is a hypothetical analytical damper whose parameters are determined optimally using a multi-objective optimization technique Non-dominated Sorting Genetic Algorithm II (NSGA II). The hysteretic behaviour of the MR damper is characterized using Bingham and modified Bouc-Wen models. The multi-objective optimization problem is solved by minimizing the difference between the root mean square (rms) sprung mass acceleration, suspension stroke and the road holding responses of the quarter car model with the MR damper and those of the active suspension system based on linear quadratic regulator (LQR) control with the constraint that the MR damper control force lies between ±5 percent of the LQR control force. It is observed that the MR damper suspension systems with optimal parameters perform an order of magnitude better than the passive suspension and perform as well as active suspensions with limited state feedback and closer to the performance of fully active suspensions.

Seismic Fragility Relationships of a Cable-Stayed Bridge Equipped with Response Modification Systems

This paper presents the development of fragility curves of a benchmark cable-stayed bridge retrofitted with response modification systems. Fragility relationships are an accepted technique used for seismic risk assessment of structures. The example used herein is a benchmark cable-stayed bridge. Synthetic ground motions are used to excite the structure. Semiactive control is applied to the structure to evaluate and quantify its impact on response mitigation. The semiactive devices used herein are magnetorheological (MR) dampers. The performance of the structure retrofitted with MR dampers is compared with the structure retrofitted with passive, active, and no devices. Fragility relationships based on deck displacement, deck shear, and overturning moment are investigated for comparison. Analyses of peak and time history responses are used to support the accuracy of the fragility relationships. An investigation of the cables exceeding an appropriate tension range and control effort required for the control cases is also provided. The resulting fragility relationships show that MR dampers are effective at mitigating the effects of seismic excitation on the cable-stayed bridge.

D19 目標制御出力に着目したセミアクティブ振動制御(M-OS2-3 セミアクティブ制御,M-OS2 建築・建設構造物の耐震・免震・制振,「海を越え,国を越え,世代を超えて!」)

As a method for semi-active control of structural systems, the active-control-based method that emulates the control force of a targeted active control law by semi-active control devices has been studied. In the active-control-based method, the semi-active control devices are not necessarily able to generate the targeted active control force because of the dissipative nature of those devices. In such a situation, the meaning of the targeted active control law becomes unclear in the sense of the control performance achieved by the resulting semi-active control system. In this study, a new semi-active control strategy that approximates the control output (not the control force) of the targeted active control is proposed. The variable parameter of the 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 targeted active control as much as possible. Parameters of the targeted active control law are optimized in the premise of the above "output emulation" strategy so that the control performance of the semi-active control becomes good and the "error" of the achieved control performance between the targeted active control and the semi-active control becomes small.

Experimental study of semiactive VSC techniques for vehicle vibration reduction

Semiactive vehicle suspension with magnetorheological dampers is a promising technology for improving the passenger comfort of a ground vehicle. In this work we consider the problem of vibration suppression in suspension systems of an experimental platform called semiactive suspension system (SAS). The system under study is equipped with a magnetorheological damper which is used as a semiactive nonlinear device. Three different variable structure controllers are proposed and experimentally tested. Experimental results show that the vibration of the suspension system is well controlled with the semiactive VSC. Furthermore, it is found that the implementation of the controllers implies a better performance than the use of a purely passive device. Despite the performance of all the controllers is comparable, the one based on the updating term yields the best results among them all.

Simultaneous Optimal Design of the Lyapunov-Based Semi-Active Control and the Semi-Active Vibration Control Device: Inverse Lyapunov Approach

We address a simultaneous optimal design problem of a semi-active (SA) control law and design parameters in a semi-active control device for civil structures. The vibration control device (VCD) that is being developed by authors is used as the semi-active control device. The VCD is composed of a ball screw with a flywheel for the inertial resistance force and an electric motor with an electric circuit for the damping resistance force. A new bang–bang type semi-active control law referred to as inverse Lyapunov approach is proposed. In the inverse Lyapunov approach, the Lyapunov matrix in the bang–bang type semi-active control based on the Lyapunov function is searched so that the control performance of the semi-active control system is optimized. Design parameters to determine the Lyapunov function and those of the VCD are optimized with the genetic algorithm (GA). The effectiveness of the proposed approach is presented with simulation studies.