Actuators For Vibration Control Research Articles

Multi-modal control and position optimization of solar panels

This paper investigates the impact of the position of piezoelectric actuators on the vibration control effect of the membrane plane composed of solar sail materials with a given unit area. Firstly, the nonlinear vibration equation of the membrane structure is perfected based on the system equation established by Yifan Lu et al. Then, the modal coupling effect pointed out by Liu Xiang is considered, and the fourth-order modal displacement generated by the piezoelectric actuator in vibration control is derived. Subsequently, the sliding mode controller used in vibration control is designed based on Lyapunov stability theory, and its effectiveness is verified through Simulink simulation. The sliding mode controller is used to calculate the required excitation signal and apply it to the piezoelectric patches. The reverse force is generated through the inverse piezoelectric effect of the patches to actively suppress the vibration of the solar sail. By changing the position and size of each piezoelectric actuator on the solar sail plane, this paper compares the impact of different layout positions on vibration control, and proposes an optimal layout scheme for the position of the piezoelectric patches in terms of control effectiveness.

The Actuating Characteristics of Magnetorheological Fluids Subjected to Particle Sedimentation and Temperature Variation

Magnetorheological (MR) fluids are known for their controllable characteristics under the influence of magnetic fields and, hence, widely used as semi-active actuators for vibration control. Regardless of advantages such as fast response time and reversible property, MR fluids inevitably experience sedimentation caused by significant density mismatches between magnetic particles and carrier liquids. Moreover, the effect of the temperature on actuating characteristics is also one of the problems to be resolved for practical implementation. This study experimentally investigates the sedimentation behavior under various temperatures ranging from 25 to 70 °C using a multiguide-arm magnetic device that generates a uniform magnetic flux density across MR fluids. The sedimentation stability is then observed after 168 h at current inputs of 0, 1, and 2 A, respectively. Subsequently, the field-dependent rheological properties of MR fluids are evaluated using a rheometer and discussed, showing actuating capability, which depends on the viscosity, shear stress, and yield stress before (initial state) and after the sedimentation (sedimentation state). The field-dependent yield stresses, which directly represent the actuating force of the semi-active actuator, are specifically evaluated. Under the on-state condition (2 A) at a temperature of 70 °C, the yield stress decreased from 2.747 kPa (initial state) to 2.352 kPa (sedimentation state). By using this yield stress, the field-dependent damping force was evaluated, showing a decrement from 1672 N (initial state) to 1623 N (sedimentation state) at a velocity of 0.8 m/s. It is shown that the temperature causes the reduction of the actuating properties after the long-term operation. The insightful findings achieved in this work will provide useful information for the evaluation of actuating characteristics of smart MR fluids and the design of MR application systems subjected to particle sedimentation and temperature variation.

Shape feature controlled topology optimization of attached piezoelectric actuators for vibration control of thin-walled smart structures

This paper proposes a method for shape feature controlled topology optimization of attached piezoelectric actuators of thin-walled smart structures, aiming at both vibration control performance as well as possible manufacturing constraints. This paper first proposes a modified K-means clustering method to derive the shape feature control functions. Then, an optimization model with system performance index (SPI) as its objectiveness and shape feature control functions as its explicit constraints is organized. Based on the Lyapunov equation, the adjoint method and the chain rule, the sensitivity analysis of both objective and constraints in optimization model is performed. A mathematical programming method is applied to solve the optimization model once the sensitivities is calculated. Then the LQR control algorithm is used in the optimized structure for vibration control. Numerical examples as well as engineering application are applied to prove effectiveness of the proposed methods. The results show feasibility of the proposed methods.

Perfect collocation using self-sensing electromagnetic actuator: Application to vibration control of flexible structures

Collocated control has the advantages of robustness and guaranteed stability. In collocated control, the sensor and actuator are placed close to each other. True collocation can be achieved using self-sensing in which the actuator can also be used as a sensor. In this article, we present a self-sensing electromagnetic actuator for vibration control of flexible structures. The back electromotive force (emf) generated in the coil is measured to evaluate the velocity of the structure (and hence, the displacement). The position measurements obtained from self-sensing are found to have good correlation with those obtained using an eddy current sensor. The efficacy of the proposed technique has been verified for the vibration control of a flexible cantilever beam. Self-sensing offers economical, simple and robust control architecture. It can be effectively used for applications where sensors and actuators cannot be collocated due to space and size limitations.

Active Seat Suspension for Ultra-Compact Mobility (Analytic Consideration on Actuator for Vibration Control)

Active Seat Suspension for Ultra-Compact Mobility (Analytic Consideration on Actuator for Vibration Control)

Development of a two degrees-of-freedom linear oscillatory actuator for vibration control

Development of a two degrees-of-freedom linear oscillatory actuator for vibration control

Design of dielectric elastomer actuators for vibration control at high frequencies

This study evaluates the basic characteristics of smart structures composed of dielectric elastomer actuators (DEAs) to suppress vibrations. A DEA, which is a lightweight, flexible polymer that can induce high deformations, should realize next-generation actuators. Additionally, DEA can achieve vibration control of structures with complex shapes or curved surfaces. Herein the performance and efficacy of DEAs are evaluated as an actuator for vibration control at high frequencies. First, the appropriate DEA structure is considered. Second, the control system for the smart structure using the DEA is modeled and designed as an actuator. Third, a method to determine DEA's optimum arrangement and shape is discussed by focusing on the structure's strain energy. Finally, a control simulation and a control experiment validate the vibration suppression effects and the efficacy of the DEA.

Characteristics Analysis of 2 DOF Linear Oscillatory Actuator for Vibration Control

In automobiles, multi axis vibration is generated because there consists of many mechanical parts. In previous study, the vibration was actively controlled by using some linear oscillatory actuators. So, we propose a 2 degrees of freedom linear oscillatory actuator to control the vibration, that achieves downsizing and weight saving. In this paper, the construction and operation principle of the proposed actuator are described. Next, the teeth shape is discussed for increasing constancy of thrust against mover’s position. Finally, it is clarified that the characteristics are enough for actively controlling undesirable multi axis vibration, through analyzed results.

Parametric study on the optimal tuning of an inertial actuator for vibration control of a plate: Theory and experiments

This paper presents a theoretical and experimental tuning of the velocity feedback gain of a plate with an inertial actuator. The objective of the study is to analyse a direct velocity feedback control unit, which can be tuned locally and yet providing a global vibration reduction. This is achieved through the knowledge of the velocity signal and the actuator dynamics, without information on the plate dynamics. In practice, an electrical input is provided to the actuator, proportional to the local velocity of the structure, in such a way to generate active damping. The tuning is performed by maximising the power absorbed by the inertial actuator from the structure, and this is shown to be equivalent to the minimisation of the global level of vibration, estimated through the kinetic energy of the structure. Nine accelerometers have been used, and the performance for several values of different feedback gains has been investigated. Moreover, the influence of the frequency range of integration in the tuning of the velocity feedback gain is considered, and it is found experimentally that a broadband reduction up to 5 dB can be achieved, as expected from the numerical model. The absorbed power from the plate by the control unit is found to be negative below the first natural frequency of the inertial actuator, when the feedback control is implemented. This is due to the fact that, although a collocated velocity feedback is implemented, the control system is only conditionally stable because of the actuator dynamics. The performance of active control is found to reduce dramatically, if instability occurs for gains lower than the optimal one. For this reason, the work is enriched with a parametric study on the plate-actuator pair, in which the influence of the dynamic properties of the plate and the inertial actuator are investigated. The effectiveness of the active control is found to depend on the mass ratio between the actuator and the plate. In particular, for low mass ratios, the system well approximate the ideal case, in which a control force is proportional to the velocity of the plate, but for high mass ratios, a small amount of active damping can be introduced.

Comparison of Three Different Techniques for Nonlinear Position and Vibration Control of a Rotating Smart Beam

In this paper, position and vibration control of a smart rotating flexible beam-like structure is investigated. The nonlinear integro-partial differential governing equations of motion are derived via the Extended Hamilton’s Principle. A State-Dependent Riccati Equation (SDRE) based methodology is used in order to design a nonlinear controller. Three different techniques are considered for comparison: (1) control torque is applied at the rotating axis for angular position and vibration control (2) control torque is applied at the rotating axis for angular position control and a distributed moment is applied via piezoelectric actuator for vibration control and (3) control torque is applied at the rotating axis for angular position and vibration control and a distributed moment is applied via piezoelectric actuator for vibration control.

Displacement Control of Photostrictive Actuators for Vibration Control with the Aid of Fuzzy Logic Control along with PSO Algorithm

Vibration in industrial equipment can be continuously monitored for unusual types of operating conditions and the resultant potential failures. Photo restrictive materials, exhibiting light-induced strains, are of interest for future generation wireless remote control photo-actuators, micro-actuators, and micro-sensors applications that exhibit large photo restriction under uniform illumination of ultraviolet light. In our proposed method, we are using fuzzy logic to illustrate the light intensity based on which the distance between the two modes is reduced using Particle Swarm Optimization (PSO) algorithm in such a way as to provide a lesser vibration result. In our proposed technique, the input is used as the velocity of the source and the displacement of the modes, the corresponding output being the light intensity. The optimal light intensity is chosen based on the displacement by means of which the corresponding displacement is again optimized to an extent desired using PSO algorithm to get further reduced vibration in the output. The accuracy of the PSO is done by comparing the result with normalized value and with the Genetic Algorithm and has proved that our proposed method produces optimal result. Thus our proposed method is projected to increase the efficiency in the output with a significant reduction in displacement.

A comparative study on the smart damping capabilities of cylindrically orthotropic piezoelectric fiber–reinforced composite actuators in vibration control of simply supported/fully clamped isotropic annular plate

For active control of vibration of plane structures of revolution, a cylindrically orthotropic piezoelectric fiber–reinforced composite actuator is addressed in a recent study. Some other available piezoelectric composites, which are originally constructed in Cartesian coordinate frame, can also be reconstructed in polar coordinate frame for similar application. Making use of all these piezoelectric composites in polar coordinate frame of an annular plate, a comparative study on their control capabilities is performed at present. All the piezoelectric composites are used in the form of patches which are optimally configured over the host plate surface and utilized as smart dampers. The geometrical and material properties of the piezoelectric composites are taken in uniform manner and the corresponding electric fields in function of applied voltage are evaluated for derivation of a closed-loop finite element model of the smart annular plate. First, the patches of every piezoelectric composite are optimally configured through the proposition of a new methodology. Next, the control/damping capabilities of the piezoelectric composites are evaluated for fundamental symmetric/asymmetric mode of vibration of the plate. The numerical results first illustrate the implementation and suitability of the present methodology for optimal size and locations of actuator patches. Subsequently, the results demonstrate damping capabilities of all the piezoelectric composites to label potential ones.

Performance of a short piezoelectric fiber–reinforced composite actuator in vibration control of functionally graded circular cylindrical shell

For improved flexibility and conformability of piezoelectric fiber–reinforced composite actuator, it is reconstructed in a recent study by the use of short piezoelectric fibers (short piezoelectric fiber–reinforced composite) instead of continuous fibers (continuous piezoelectric fiber–reinforced composite). This modification facilitates its application in short piezoelectric fiber–reinforced composite layer form instead of continuous piezoelectric fiber–reinforced composite patch form particularly in case of host structures with highly curved boundary surfaces. But the corresponding change in actuation capability is a major issue for potential application of short piezoelectric fiber–reinforced composite that is studied in this work through the control of vibration of a functionally graded circular cylindrical shell under thermal environment. First, an arrangement of continuous piezoelectric fiber–reinforced composite actuator patches over the host shell surface is presented with an objective of controlling all modes of vibration. Next, the use of short piezoelectric fiber–reinforced composite actuator layer for similar control activity is demonstrated through an arrangement of electrode patches over its surfaces. Subsequently, an electric potential function is assumed for the consideration of electrode patches and a geometrically nonlinear coupled thermo-electro-mechanical incremental finite element model of the harmonically excited overall functionally graded shell is developed. The numerical results reveal actuation capability of short piezoelectric fiber–reinforced composite actuator layer with reference to that of the existing continuous piezoelectric fiber–reinforced composite/monolithic piezoelectric actuator patches. The effects of temperature, size of electrode patches, properties of piezoelectric fiber–reinforced composite, and functionally graded properties on the control activity of short piezoelectric fiber–reinforced composite/continuous piezoelectric fiber–reinforced composite actuator are also presented.

Tethered actuator for vibration control of space structures

Effectiveness of a micro-tension actuator for vibration control of such flexible space structures as the tethered space solar power satellites is experimentally studied on the ground. A flexible leverage is employed as the micro-tension actuator in order to control the microtension of tether. The flexible leverage is connected through a tether to the flexible beam as an experimental model of the flexible solar panel with the low first modal frequency of order 1Hz. The nonlinearity of the flexible tether is taken into account for the vibration control since the tether becomes ineffective when it slacks, i.e., when it is tension-free. The feedback controller is designed by means of the Mission Function control algorithm. Flexural rigidity of the flexible leverage plays an important role in the vibration suppression and is studied experimentally to shed light on the effectiveness of the leverages with five different kinds of rigidity. The experimental results show not only the effect of the flexural rigidity of the flexible leverage on the control performance of the vibration suppression but also the importance of selection of the rigidity to control the vibration of tethered flexible space structures through the microtension of tethers in space.

Experimental Study on the Magnetic Characteristics of Magnetic Shape Memory Alloy Materials

With shape memory function of new smart material, the magnetic control properties of magnetic shape memory alloy could be used to fabricate intelligent actuators for vibration control of structures. In order to study its magnetic properties, this text selected Ni53Mn25Ga22 as the material for the research and development of actuator drive, And two MSMA test specimens were prepared for the experimental study under the coupled action of the temperature, preload pressure and magnetic field. The results showed that the strain of MSMA induced by magnetic field decreased with the increase of the preload pressure at constant magnetic field. The deformation performance was best when the magnetic induction intensity was about 0.5T. And the constitutive relations were fitted for the actuator production to lay the foundation for later.

Experimental Study on the Magnetic Properties of MSMA and the Function of MSMA Actuator of Reticulated Shell Structure

With shape memory function of new smart material, the magnetic control properties of magnetic shape memory alloy could be used to fabricate intelligent actuators for vibration control of reticulated shell structure. The major performance parameters of the microstructure of the materials has been considered in the functional relationship between the magnetic field and strain model of traditional magnetic shape memory alloys (MSMA). But the magnetic field of MSMA do not considered, induced strain and pre-pressure, ambient temperature and other factors, which is a mutual restraint relationship and coupling. Selected Ni53Mn25Ga22, in this paper, as the material for the research on deformation under the action of temperature, magnetic field, pressure coupling effect, and according to the test data designed a MSMA actuator drive.

A new optimal sliding mode controller design using scalar sign function

This paper presents a new optimal sliding mode controller using the scalar sign function method. A smooth, continuous-time scalar sign function is used to replace the discontinuous switching function in the design of a sliding mode controller. The proposed sliding mode controller is designed using an optimal Linear Quadratic Regulator (LQR) approach. The sliding surface of the system is designed using stable eigenvectors and the scalar sign function. Controller simulations are compared with another existing optimal sliding mode controller. To test the effectiveness of the proposed controller, the controller is implemented on an aluminum beam with piezoceramic sensor and actuator for vibration control. This paper includes the control design and stability analysis of the new optimal sliding mode controller, followed by simulation and experimental results. The simulation and experimental results show that the proposed approach is very effective.

An algorithm for LQ optimal actuator location

The locations of the control hardware are typically a design variable in controller design for distributed parameter systems. In order to obtain the most efficient control system, the locations of control hardware as well as the feedback gain should be optimized. These optimization problems are generally non-convex. In addition, the models for these systems typically have a large number of degrees of freedom. Consequently, existing optimization schemes for optimal actuator placement may be inaccurate or computationally impractical. In this paper, the feedback control is chosen to be an optimal linear quadratic regulator. The optimal actuator location problem is reformulated as a convex optimization problem. A subgradient-based optimization scheme which leads to the global solution of the problem is used to optimize actuator locations. The optimization algorithm is applied to optimize the placement of piezoelectric actuators in vibration control of flexible structures. This method is compared with a genetic algorithm, and is observed to be faster and more accurate. Experiments are performed to verify the efficacy of optimal actuator placement.

Modelling and testing of a dielectic electro-active polymer (DEAP) actuator for active vibration control

Passive vibration absorbers are really effective only at the tuned frequency. This limit is overcome by adaptive absorbers which offer the possibility to adjust their behaviour according to needs. The paper focuses on a smart actuator for vibration control made up by a dielectric electro-active polymer (DEAP). The DEAP is obtained constraining a silicone corrugated sheet between two silver layers and it is manufactured by Danfoss Polypower A/S. The actuator is fabricated by rolling the DEAP sheet in a cylindrical and core-free shape. The paper describes the static and dynamic characterizations of the actuator. A theoretical model is developed by considering the actuator as a multi-elements model. Moreover, a modal test of the actuator is performed driving it with an electro-dynamic shaker in a frequency range up to 1 kHz. A good agreement between theoretical and experimental data is obtained at lower frequencies. Stiffness and damping laws of the actuator are determined by fitting theoretical expectations and test results. The actuator is proved useful for controlling vibrations at low frequencies because it shows internal resonances at frequencies above 75 Hz. Finally, first results about the use of the DEAP actuator for vibration control of harmonic excitations in a band-limited frequency range below 10 Hz are reported.

Extending the operation range of electrorheological actuators for vibration control through novel designs

Electrohydraulic actuators with electrorheological fluids were lately introduced for active vibration decoupling. They are suited especially for active isolation of heavy machines and apparatuses. Compared to conventional electrodynamic or hydraulic actuators, these electrorheological systems have considerable advantages because of very high force density and broad frequency range. However, the potential of the electrorheological technology does not remain used up to now completely. In this study, new designs are introduced, which extend the operation borders of the electrorheological actuators for vibration decoupling by utilization of hydrostatic as well as to hydrodynamic forces. The theoretically determined dynamic behaviors of the new actuator principles form the basis for the choice and adaptation of the electrohydraulic systems to special vibration isolation problems and show the advantages to conventional hydraulic actuators.