A Review on Recent Active Vibration Control Techniques
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paper_title: Hybrid Active Vibration Control of Rotorbearing Systems Using Piezoelectric Actuators

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The vibrations of a flexible rotor are controlled using piezoelectric actuators. The controller includes active analog components and a hybrid interface with a digital computer. The computer utilizes a grid search algorithm to select feedback gains that minimize a vibration norm at a specific operating speed. These gains are then downloaded as active stiffnesses and dampings with a linear fit throughout the operating speed range to obtain a very effective vibration control.
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paper_title: Active vibration control of cantilever beam by using PID based output feedback controller

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Undesired noise and vibrations have a detrimental effect in many areas. Hence the control of vibrations has become a relevant technological challenge. Active vibration control of structures using smart materials is especially in vogue. This involves sensing the motion of the structure using sensors, generating a control signal using a controller and applying a control force on the structure using actuators. To design the control system of any vibrating structure, the mathematical model of the system is required. However, it is difficult to theoretically construct a model of complex structures. On the other hand, it is relatively simpler to model such systems in a Finite Element (FE) environment like ANSYS©. This paper deals with the extraction of the full and reduced mathematical models of a cantilever beam into MATLAB© from its FE model. The full model of the beam is reduced by discarding those modes which do not contribute to the overall response. It is found that the frequency and transient responses o...
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paper_title: Integral Twist Actuation of Helicopter Rotor Blades for Vibration Reduction

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2001.
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paper_title: Robust integral variable structure controller and pulse-width pulse-frequency modulated input shaper design for flexible spacecraft with mismatched uncertainty/disturbance

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This paper presents a dual-stage control system design method for the flexible spacecraft attitude maneuvering control by use of on-off thrusters and active vibration control by input shaper. In this design approach, attitude control system and vibration suppression were designed separately using lower order model. As a stepping stone, an integral variable structure controller with the assumption of knowing the upper bounds of the mismatched lumped perturbation has been designed which ensures exponential convergence of attitude angle and angular velocity in the presence of bounded uncertainty/disturbances. To reconstruct estimates of the system states for use in a full information variable structure control law, an asymptotic variable structure observer is also employed. In addition, the thruster output is modulated in pulse-width pulse-frequency so that the output profile is similar to the continuous control histories. For actively suppressing the induced vibration, the input shaping technique is used to modify the existing command so that less vibration will be caused by the command itself, which only requires information about the vibration frequency and damping of the closed-loop system. The rationale behind this hybrid control scheme is that the integral variable structure controller can achieve good precision pointing, even in the presence of uncertainties/disturbances, whereas the shaped input attenuator is applied to actively suppress the undesirable vibrations excited by the rapid maneuvers. Simulation results for the spacecraft model show precise attitude control and vibration suppression.
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paper_title: Experimental study on active vibration control of a single-link flexible manipulator using tools of fuzzy logic and neural networks

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This paper is concerned with the design and implementation of active vibration control based on fuzzy logic and neural networks (NNs). The controller is used to dampen the end-point vibration in a single-link flexible manipulator mounted on a two degrees-of-freedom platform. The inputs to the fuzzy logic controller (FLC) are the angular position of the hub and the end point deflection of the flexible beam. A NN predicting the deflection was obtained using a set of three strain gauge pairs mounted on the beam and an linear-variable differential transformer placed at the tip. This paper discusses how to build the rule base for the flexible beam based on the relation between the angular displacement of the hub and the end-point deflection, as well as the approach that was used to develop the NN model. Several experimental results showing the effectiveness of the FLC in reducing the end-point vibration of the flexible beam are presented.
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paper_title: Analysis of active vibration control in smart structures by ANSYS

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It is possible to model smart structures with piezoelectric materials using the product ANSYS/Multiphysics. In this study, the integration of control actions into the ANSYS solution is realized. First, the procedure is tested on the active vibration control problem with a two-degrees of freedom system. The analytical results obtained by the Laplace transform method and by ANSYS are compared. Then, the smart structures are studied by ANSYS. The input reference value is taken as zero in the closed loop vibration control. The instantaneous value of the strain at the sensor location at a time step is subtracted from zero to find the error signal value. The error value is multiplied by the control gain to calculate the voltage value which is used as the input to the actuator nodes. The process is continued with the selected time step until the steady-state value is approximately reached. The results are obtained for the structures analyzed in other studies. The active vibration control of a circular disc is also studied.
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paper_title: Vibration Suppression in a Two-Mass Drive System Using PI Speed Controller and Additional Feedbacks—Comparative Study

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In this paper, an analysis of control structures for the electrical drive system with elastic joint is carried out. The synthesis of the control structure with proportional-integral controller supported by different additional feedbacks is presented. The classical pole-placement method is applied. Analytical equations, which allow for calculating the control structure parameters, are given. The limitation of the design due to the number of degrees of freedom of the considered drive systems is shown. In order to damp the torsional vibration effectively, the application of the feedback from one selected state variable is necessary. In the literature, a large number of possible feedbacks have been reported. However, in this paper, it is shown that all systems with one additional feedback can be divided into three different groups, according to their dynamical characteristics. In addition, the system with two additional feedbacks is investigated. The comparison between considered structures is carried out. The simulation results are confirmed experimentally in the laboratory setup
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paper_title: Positive position feedback (PPF) controller for suppression of nonlinear system vibration

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In this paper, a study for positive position feedback controller is presented that is used to suppress the vibration amplitude of a nonlinear dynamic model at primary resonance and the presence of 1:1 internal resonance. We obtained an approximate solution by applying the multiple scales method. Then we conducted bifurcation analyses for open and closed loop systems. The stability of the system is investigated by applying the frequency-response equations. The effects of the different controller parameters on the behavior of the main system have been studied. Optimum working conditions of the system were extracted to be used in the design of such systems. Finally, numerical simulations are performed to demonstrate and validate the control law. We found that all predictions from analytical solutions are in good agreement with the numerical simulation. A comparison with the available published work is included at the end of the work.
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paper_title: Dynamics and power flow behaviour of a nonlinear vibration isolation system with a negative stiffness mechanism

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Abstract The dynamics and power flow behaviour of a nonlinear vibration isolation system with a negative stiffness mechanism (NSM) are studied. The mathematical equations governing the nonlinear dynamics of the system are derived. The averaging method is used to obtain the frequency response function of the system subject to harmonic excitations. It is found that adding NSM can greatly enlarge the frequency band for effective vibration isolation. Numerical simulations reveal that sub-harmonic resonance may occur even when the excitation frequency is well above the natural frequency of the linearized system. As the effects of sub-harmonic response cannot be reflected by the averaging formulations, numerical integrations are used to obtain the dynamic responses including sub-harmonic and other frequency components. Furthermore, power flow characteristics of this nonlinear isolation system are examined for a better assessment of the isolation performance. The results show that the occurrences of sub-harmonic resonance may considerably increase both the time-averaged input power and the maximum kinetic energy. Compared with linear systems, the power flows of the nonlinear system might be non-unique and sensitive to the initial conditions. Some suggestions on restricting the maximum deflection and suppressing sub-harmonic resonances are provided for effective designs of nonlinear isolation systems.
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paper_title: Nonlinear vibration semi-active control of automotive steering using magneto-rheological damper

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Traffic accidents are often caused by vibration of automotive steering because the vibration can make a vehicle run like a snake. A novel semi-active vibration control strategy of automotive steering with magneto-rheological (MR) damper is proposed in this paper. An adaptive RBF neural sliding mode controller is designed for the vibration system. It is showed that an equivalent dynamic model for the vibration system is established by using Lagrange method, and then treats it as actual system partially. A feedback control law is designed to make this nominal model stable. Uncertain part of system and outside disturbance are estimated using RBF neural network, and their upper boundary is obtained automatically. By constructing reasonable switch function, state variables can arrive at origin asymptotically along the sliding mode. Strong robust character of control system is proved by stability analysis and a numerical simulation example is performed to support this control scheme.
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paper_title: Output frequency response function based design of additional nonlinear viscous dampers for vibration control of multi-degree-of-freedom systems

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Abstract This paper is concerned with the development of a new technique for the optimal placement and design of additional nonlinear viscous dampers for vibration control of Multi-Degree-Of-Freedom (MDOF) systems. The MDOF systems described by a multi-storey shear building model and subjected to harmonic loadings are first considered in the present study; then, the basic ideas of the design are extended to the cases of earthquake loadings. The studies are based on the concept of Output Frequency Response Function (OFRF) and associated methods proposed recently by the authors in control engineering and extend, for the first time, the well-established linear viscous damper optimal placement and design techniques for MDOF system vibration control to the nonlinear case. The design examples verify the effectiveness of the new technique, and demonstrate the beneficial effects of the designed additional nonlinear dampers on the MDOF system vibration control and the advantages of nonlinear viscous dampers over linear dampers in such applications.
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paper_title: Vibration control of a transversely excited cantilever beam with tip mass

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The problem of controlling the vibration of a transversely excited cantilever beam with tip mass is analyzed within the framework of the Euler–Bernoulli beam theory. A sinusoidally varying transverse excitation is applied at the left end of the cantilever beam, while a payload is attached to the free end of the beam. An active control of the transverse vibration based on cubic velocity is studied. Here, cubic velocity feedback law is proposed as a devise to suppress the vibration of the system subjected to primary and subharmonic resonance conditions. Method of multiple scales as one of the perturbation technique is used to reduce the second-order temporal equation into a set of two first-order differential equations that govern the time variation of the amplitude and phase of the response. Then the stability and bifurcation of the system is investigated. Frequency–response curves are obtained numerically for primary and subharmonic resonance conditions for different values of controller gain. The numerical results portrayed that a significant amount of vibration reduction can be obtained actively by using a suitable value of controller gain. The response obtained using method of multiple scales is compared with those obtained by numerically solving the temporal equation of motion and are found to be in good agreement. Numerical simulation for amplitude is also obtained by integrating the equation of motion in the frequency range between 1 and 3. The developed results can be extensively used to suppress the vibration of a transversely excited cantilever beam with tip mass or similar systems actively.
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paper_title: Hybrid time-domain and spatial filtering nonlinear damping strategy for efficient broadband vibration control

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Limiting low-frequency vibrations with low-energy, yet efficient strategies is of prior importance in embedded devices, such as on-board electronics. Hence, particular attention has been paid over the few last decades to electromechanical materials able to convert mechanical energy into electricity, therefore reducing the mechanical energy within the structure yielding a damping effect. However, under multimodal or more generally broadband vibration spectra, the performance of such systems is compromised. Hence, the purpose of this paper is to expose an efficient nonlinear technique based on the intermittent voltage inversion of a piezoelectric element voltage through switching actions. In order to achieve very good performance under broadband vibrations, spatial and time domain filtering approaches are implemented within the control of the digital switches, allowing simultaneous mode separation thanks to the spatial filtering process and better energy transfer due to the processing of the time history of...
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paper_title: Adaptive Sliding-Mode Control for Nonlinear Active Suspension Vehicle Systems Using T–S Fuzzy Approach

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This paper deals with the adaptive sliding-mode control problem for nonlinear active suspension systems via the Takagi-Sugeno (T-S) fuzzy approach. The varying sprung and unsprung masses, the unknown actuator nonlinearity, and the suspension performances are taken into account simultaneously, and the corresponding mathematical model is established. The T-S fuzzy system is used to describe the original nonlinear system for the control-design aim via the sector nonlinearity approach. A sufficient condition is proposed for the asymptotical stability of the designing sliding motion. An adaptive sliding-mode controller is designed to guarantee the reachability of the specified switching surface. The condition can be converted to the convex optimization problems. Simulation results for a half-vehicle active suspension model are provided to demonstrate the effectiveness of the proposed control schemes.
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paper_title: Vibration Control of Smart Structure Using Sliding Mode Control with Observer

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This paper studies the application of the sliding mode control method to reduce the vibration of flexible structure with piezoelectric actuators and strain gage transducer in practical complex environment. The state- space dynamic model of the system was derived by using finite element method and experimental modal test. The structure is subjected to arbitrary, unmeasurable disturbance forces. Taking into account the uncertain random disturbance and measurement noise, Kalman filter is chosen as the state estimator to obtain the modal coordinates and modal velocities for the modal space control. A sliding mode controller is adopted due to its distinguished robustness property of insensitiveness to parameter uncertainties and external disturbances. The sliding surface is determined by using optimization method, and the sliding controller is designed by applying Lyapunov direct method. That is, along the switching surface, the cost function of the states is minimized. A real-time control system was built using dSPACE DS1103 platform, and vibration control tests were performed to experimentally verify the performances of the proposed controller. The results of experiment show the controller can effectively attenuate elastic vibration of the structure.
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paper_title: Nonlinear Vibration Control of Flexible Structures Using Nonlinear Modified Positive Position Feedback Approach

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A new Nonlinear Modified Positive Position Feedback (NMPPF) controller is proposed in this paper to suppress the nonlinear resonant vibrations in flexible structures. The NMPPF uses a nonlinear second-order feedback compensator to overcome the vibrations at exact primary resonance frequency, and a first-order integrating term to lower the remaining peak amplitudes in the frequency domain. For the closed-loop system, an innovative implementation of the Method of Multiple Scales is employed to obtain the modulation equations. Results demonstrate the superior performance of the NMPPF controller compared to the conventional approach i.e. Positive Position Feedback (PPF), as the suppression performance is improved by 62% in the peak amplitude reduction. The presented parameter analysis of the NMPPF controller also proposes the optimal controller parameters to provide the highest suppression level in the nonlinear oscillatory system.© 2014 ASME
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paper_title: Nonlinear vibration control and energy harvesting of a beam using a nonlinear energy sink and a piezoelectric device

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Abstract This paper presents an optimal design for a system comprising a nonlinear energy sink (NES) and a piezoelectric-based vibration energy harvester attached to a free–free beam under shock excitation. The energy harvester is used for scavenging vibration energy dissipated by the NES. Grounded and ungrounded configurations are examined and the systems parameters are optimized globally to both maximize the dissipated energy by the NES and increase the harvested energy by piezoelectric element. A satisfactory amount of energy has been harvested as electric power in both configurations. The realization of nonlinear vibration control through one-way irreversible nonlinear energy pumping and optimizing the system parameters result in acquiring up to 78 percent dissipation of the grounded system energy.
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paper_title: Nonlinear vibration suppression of flexible structures using nonlinear modified positive position feedback approach

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This paper introduces Nonlinear Modified Positive Position Feedback (NMPPF) control approach for nonlinear vibration suppression at primary resonance. Nonlinearity in the system is due to large deformations caused by high-amplitude disturbances, while this control approach is applicable to all types of nonlinearities in resonant structures. NMPPF controller consists of a resonant second-order nonlinear compensator, which is enhanced by a lossy integrating compensator. The two compensators create a combination of exponential and periodic control inputs, which needs innovative time scaling for using the Method of Multiple Scales to obtain the analytical solution of the closed-loop system. The results of the analytical solution for the closed-loop NMPPF controller are presented and compared with the result of the conventional PPF controller. Effects of the control parameters on the system response are comprehensively studied by parameter variations. The approximate solution is then verified using numerical simulations. According to the results, the NMPPF controller provides a higher level of suppression in the overall frequency domain, as the peak amplitude at the neighborhood frequencies of the primary mode is reduced by 44 %, compared to the PPF method. The tunable control parameters also give more flexibility to create the expected type of system response.
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paper_title: 1:2 and 1:3 internal resonance active absorber for non-linear vibrating system

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Abstract Vibration and dynamic chaos should be controlled in either structures or machines. An active vibration absorber for suppressing the vibration of the non-linear plant when subjected to external and parametric excitations is studied in the presence of one-to-two and one-to-three internal resonance. The main attention is focused on the study of the active control and stability of two systems, which can be used to reduce vibrations due to rotor blade flapping motion. The method of multiple scale perturbation technique is applied to determine four first-order non-linear ordinary differential equations that govern the modulation of the amplitudes and phases in the presence of internal resonance of the two systems with quadratic and cubic order of control. These equations are used to determine the steady state solutions and their stability. The stability study of non-linear periodic solution for two cases (1:2 and 1:3 internal resonance) and the stability of the obtained numerical solution are investigated using frequency, force–response curves and phase-plane method. Also, effects of some parameters on the steady state solution of the vibrating system are investigated and reported in this paper. Variation of some parameters leads to the bending of the frequency, force–response curves and hence to the jump phenomenon occurrence. The reported results are compared to the available published work.
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paper_title: Nonlinear energy sink to control vibrations of an internally nonresonant elastic string

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A nonlinear elastic string is considered here as a main structure to be passively controlled using a Nonlinear Energy Sink (NES). The string is internally nonresonant due to a point mass and an elastic spring applied at a free tip, and a distributed force with harmonic time-law is assumed. The Multiple Scale/Harmonic Balance method, already introduced for finite degree of freedom systems, is extended here in direct approach, being applied to the partial differential equations ruling the dynamics of the system. Amplitude modulation equations are obtained and discussion of some solutions, where the beneficial effect of the NES is evident, are made.
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paper_title: Large amplitude vibration of carbon nanotube reinforced functionally graded composite beams with piezoelectric layers

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Large amplitude free vibration of functionally graded carbon nanotube reinforced composite (CNTRC) beams with surface-bonded piezoelectric layers subjected to a temperature change and an applied voltage is studied in this paper. The governing equations of the piezoelectric CNTRC beam are derived based on Euler-Bernoulli beam theory, von Karman geometric nonlinearity and the physical neutral surface concept. Both uniformly distribution (UD) and functionally graded (FG) distribution patterns of the single-walled carbon nanotube (SWCNT) reinforcements are considered. It is assumed that the material properties of the FG-CNTRC beam vary in the thickness direction, and that the SWCNTs are aligned and straight. Galerkin procedure is used to obtain the second order nonlinear ordinary equation in time with cubic nonlinear term. Multiple times scales method is then employed to determine the nonlinear free vibration characteristics of the beam clamped at both ends. The effects of the applied voltage, temperature change, beam geometry, the volume fraction and distribution pattern of the SWCNTs on the linear and nonlinear frequencies of the piezoelectric CNTRC beams are investigated through a comprehensive parametric study.
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paper_title: Integration of Smart Materials into Dynamics and Control of Inflatable Space Structures

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An experimental investigation of vibration testing and control of an inflated thin-film torus is presented. Lightweight inflatable structures are a viable alternative in aerospace structure design. These structures, however, pose special problems in testing and in controlling vibrations due to their extremely lightweight, flexible, and high-damping properties. In this study, we show that smart materials, which can be fully integrated into an inflatable space system, could be used as sensors/actuators in order to find modal parameters and to reduce vibrations. The results indicate the potential smart materials for use in the dynamics and control of inflated structures.
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paper_title: Control of a Space Rigidizable Inflatable Boom Using Macro-fiber Composite Actuators

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An experimental investigation of vibration testing and active control of a space rigidizable inflatable composite boom containing embedded piezoelectric composite actuators was conducted. Inflatable deployable space structures offer reduced mass, higher packaging efficiency, lower life cycle cost, simpler design with fewer parts, and higher deployment reliability for many large deployable spacecraft structures applications. Enhancing deployed precision and repeatability for these structures is an ongoing research area, in particular for rigidizable inflatable material systems. In this study, in situ vibration testing and active damping using piezoelectric macro-fiber composite actuators embedded within a typical space-rigidizable deployable composite boom are investigated The embedded macro-fiber composites are shown to be capable of surviving integration, packaging, deployment and thermal rigidization in vacuum, and subsequently operating at their full actuation capability. Positive position feedback con...
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paper_title: Vibration control of a frame structure using electro-rheological fluid mounts

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A squeeze-mode electro-rheological (ER) mount has been designed, manufactured, and applied to the vibration control of a frame structure subjected to external excitations. After verifying that the damping force of the ER mount can be controlled by controlling the applied voltage, a frame structure system supported by spring mounts and the proposed ER mounts has been assembled. The governing equation of the structural system is derived in the modal coordinate and is rewritten as a state-space control model. An optimal controller, which consists of the velocity feedback signal of the frame structure and the force feedback signal transmitted from the exciting point to the mount position, is formulated in order to attenuate the imposed excitations. The controller has been optimized experimentally and control responses such as the acceleration of the frame structure and the transmitted force at each mount position are presented in both time and frequency domains.
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paper_title: Vibration control of collocated smart structures using H ∞ modified positive position and velocity feedback

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In this paper, H∞ modified positive position feedback (HMPPF) and H∞ modified positive velocity feedback (HMPVF) controllers are developed as two innovative controllers for active vibration reduction in flexible collocated structures. The controllers use the concept of modified positive feedback and are enhanced by the H∞ feedback design to provide effective vibration suppression of multiple modes. An aluminum cantilever beam is used to experimentally evaluate the performance of the two controllers. The objective of the HMPPF controller is to suppress vibration displacement when all of the fundamental modes are excited. In this case which considers the first three modes of the flexible structure, overall vibration displacement is reduced to 38% of the uncontrolled value. The HMPVF, on the other hand, uses the control energy to reduce the vibration velocity to the lowest possible value. Vibration velocity amplitude using the HMPVF approach was reduced more than displacement, which makes this controller mor...
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paper_title: On the stability problem caused by finite actuator dynamics in the collocated control of large space structures

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As large space structures are basically distributed systems, serious consideration must be given to the very high order, and consequently very high bandwidth, of these systems. In particular, as practical active control devices such as sensors and actuators have finite bandwidth, great care must be exercised so that control of low-frequency modes does not destabilize the intermediate and higher-order modes. In this paper, the nature of these stability problems is investigated and a technique using position feedback is considered.
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paper_title: Control system of the self-mobile space manipulator

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The self-mobile space manipulator, (SM)/sup 2/, is a simple, 5-DOF, 1/3 scale, laboratory version of a robot designed to walk on the trusswork and other exterior surfaces of Space Station Freedom. It will be capable of routine tasks such as inspection, parts transportation and simple maintenance procedures. The authors have designed and built the robot and gravity compensation system to permit simulated zero-gravity experiments. The authors have developed the control system for the (SM)/sup 2/ including control hardware architecture and operating system, control station with various interfaces, hierarchical control structure, multi-phase control strategy for step motion, and various low-level controllers. The system provides operator friendly, real-time monitoring, robust control for 3-D locomotion movements of the flexible robot. A hierarchical structure allows the control to be executed in various levels autonomously or by teleoperation, and a multiphase control strategy facilitates the control in different tasks. Based on the dynamic model developed, a linear-structured joint-level controller and model-based control scheme with acceleration feedback is being implemented to provide a stable and fast motion. The configuration-independent control scheme allows the control parameters to adapt to changes in system dynamics due to the robot configuration variation. With a variety of low-level controllers which the authors developed, the system has demonstrated robustness to the uncertainties in modeling and in payload. >
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paper_title: Multi positive feedback control method for active vibration suppression in flexible structures

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Abstract This paper presents a novel controller for active vibration reduction in piezoelectric-actuated flexible structures. The new Multi Positive Feedback (MPF) control consists of two sections where each operates using a set of actuators. One section uses position and the other uses velocity feedback to perform real-time vibration control. The 90° phase difference between the feedbacks leads to non-zero resultant control output. This property results in a more effective operation of the available actuators. Sections of the MPF controller are designed based on the concept of the Modified Positive Position Feedback (MPPF) control approach, where the damping of the control system is increased by addition of a first-order term parallel to a second-order compensator. The controller is designed to simultaneously control single or multi resonant frequency vibrations. Due to the high influence of gain values on the control performance, H 2 and H ∞ norms are used to optimize these gains. For validation purposes, the controller is verified here numerically and experimentally for vibration control of a clamped–clamped beam and a cantilever at resonance. According to the results, the MPF controller has a superior performance compared to the MPPF controller, in addition to effective suppression on both vibration displacement and velocity. Using the MPF controller in multimode and by utilizing the H ∞ gain optimization method, vibration displacement amplitudes were reduced to 19.4% of the uncontrolled state for the beam.
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paper_title: Positive position feedback control for large space structures

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A new technique for vibration suppression in large space structures is investigated in laboratory experiments on a thin cantilever beam. The technique, called Positive Position Feedback (PPF), makes use of generalized displacement measurements to accomplish vibration suppression. Several features of Positive Position Feedback make it attractive for the large space structure control environment. The realization of the controller is simple and straightforward. Global stability conditions can be derived which are independent of the dynamical characteristics of the structure being controlled, i.e., all spillover is stabilizing. Furthermore, the method can be made insensitive to finite actuator dynamics, and is amenable to a strain-based sensing approach. The experiments described here control the first six bending modes of a cantilever beam, and make use of piezoelectric materials for actuators and sensors, simulating a piezoelectric active-member. Modal damping ratios as high as 20% of critical are achieved.
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paper_title: An enhanced SMA phenomenological model: I. The shortcomings of the existing models

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This paper provides an enhanced phenomenological model for shape memory alloys (SMAs), to better model their behavior in cases where the temperature and stress states change simultaneously. The phenomenological models for SMAs, consisting of a thermodynamics-based-constitutive and a phase transformation kinetics model, are the most widely used models for engineering applications. The existing phenomenological models are formulated to qualitatively predict the behavior of SMA systems for simple loadings. In this study, we have shown that there are certain situations in which these models are either not correctly formulated, and therefore are not able, to predict the behavior of SMA wires or the formulation is not straightforward for engineering applications. Such cases most often occur when the temperature and stress of the SMA wire change simultaneously, such as the case of rotary SMA actuators. To this end, a rotary SMA-actuated robotic arm is modeled using the existing constitutive models. The model is verified against the experimental results to document that the model is not able to predict the behavior of the SMA-actuated manipulator, under certain conditions.
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paper_title: Hybrid Positive Feedback Control for Active Vibration Attenuation of Flexible Structures

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A new controller is introduced in this paper as a novel method for active vibration suppression in flexible structures. The hybrid positive feedback (HPF) uses a second- and a first-order compensator that are fed by the displacement and velocity feedbacks, respectively. Parallel pairs of the HPF controller are implemented when suppression in multimode condition is issued. Since the controller uses two gains for each pair of the actuator/sensor patch for each mode, a suitable gain optimization method has to be used to ensure the optimum performance. To this end, ${\cal H}_2$ and ${\cal H}_{\infty}$ optimization approaches are utilized. For validation purposes, the controller is verified numerically and experimentally for vibration control of a cantilever beam. System identification is performed, then closed-loop system responses to simultaneous multimode and swept frequency excitations are obtained. According to the results, the HPF controller has a superior performance compared to the conventional method of positive position feedback. Vibration displacement amplitudes were reduced by more than 85% relative to the uncontrolled state. The best performance was achieved by the ${\cal H}_2$ -optimized HPF, as the net value for vibration displacement amplitude reduction in the multimode condition was 90% of the uncontrolled amplitude.
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paper_title: A mechanical microscope: High-speed atomic force microscopy

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An atomic force microscope capable of obtaining images in less than 20ms is presented. By utilizing a microresonator as a scan stage, and through the implementation of a passive mechanical feedback loop with a bandwidth of more than 2MHz, a 1000-fold increase in image acquisition rate relative to a conventional atomic force microscope is obtained. This has allowed images of soft crystalline and molten polymer surfaces to be collected in 14.3ms, with a tip velocity of 22.4cms−1 while maintaining nanometer resolution.
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paper_title: Feedback Linearization with Acceleration Feedback for a Two-Lin Flexible Manipulator

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This paper utilizes a three-loop control strategy in a decentralized fashion for each link of a two-link flexible manipulator. The first loop employs techniques from feedback linearization for the rigid dynamics, where motor dynamics are accounted for in the model and the linearizing control law. The second (outer) loop consists of a simple proportional-derivative (PD) control law for accurate rigid body angle tracking. The third outer loop employs acceleration feedback, from sensed linear acceleration at each link endpoint, to account for flexure effects. The overall scheme is relatively simple in order to facilitate easy implementation; experimental results are provided to verify the effectiveness of the developed schemes.
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paper_title: Experimental studies of vibration control of a space truss structure

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This paper presents mainly a research in the field of active damping augmentation of a four-bar, four-longern space truss structure in cantilever condition, using one active member placed at various locations in the truss structure based on the desired damping control requirements. The load-carrying active member consists of a stack of concentric piezoelectric wafers as a piezoelectric actuator and a collocated impedance head. Active damping control conducted on the truss structure was realized using collocated velocity feedback around the active member. In this paper, active member placement was determined by introducing modal dissipation energy ratio as an optimal index. Experiments were then performed to evaluate both the effectiveness of the active damping control and active member placement. Comparing the closed-loop response to the open-loop response with respect to various placements of the active member, the experimental results show that it is difficult to find a suitable location to place active member for active modal damping control effective to all modes of interest by using or placing only one active member as a controlling actuator in the truss structure. So, a multi-active-member control scheme is suggested in future research work for improvement of structural performance.
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paper_title: Discrete-time stability of continuous-time controller designs for large space structures

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References ^igneron, F.R. and Millar, R.A., "Flight Performance of the Stabilization System of the Communications Technology Satellite," Journal of Guidance and Control, Vol. 1, Nov.-Dec. 1978, pp. 404412. 2 Weber, R., "The Passive, Ground-Based, Electro-Optical Detection of Synchronous Satellites," TN-1978-27, ESD-TR-78-213, MIT Lincoln Laboratory, Lexington, Mass., June 1978. Vigneron, F.R. and Krag, W.E., "The Attitude Dynamics of Hermes After Termination of Three-Axis Stabilization," CRC Report No. 1354, Dept. of Communications, Ottawa, Canada, 1982.
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paper_title: Direct position plus velocity feedback control of large flexible space structures

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The authors demonstrate the feasibility of shape and position control of large flexible structures with collocated sensors and actuators using direct position-plus-velocity feedback. This result is important for large space structures where the number of modes is very large and eventually unknown. When the number of inputs equals the number of outputs, the stabilizing feedback gain stands for any positive definite matrix, including diagonal matrices. This result may explain the success of decentralized adaptive controllers when a reasonable number of sensors is used to satisfy the observability assumption. >
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paper_title: Direct Velocity Feedback Control of Large Space Structures

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which relates the displacements u(x,t) of the equilibrium position of a flexible structure ft (a bounded open connected set with smooth boundary dfi in /7-dimensiona l space R") to the applied force distribution F(x,t). The mass density m(x) is a positive function of the location x on the structure. The change of variables u(x,t) ^u(x,t)/m(x) l/2 eliminates m(x) without changing the properties of Eq. (1) and, henceforth, assume m(x) = \. The non-negative real number £ is the damping coefficient of the structure; it is quite small for LSS. The operator A is a symmetric, non-negative, time-invariant differential operator with compact resolvent and a square root A'/2. The domain D(A) of A contains all sufficiently differentiable functions which satisfy the appropriate boundary conditions for the LSS. D(A) is dense in the Hilbert space //=L 2 (Q) with the usual inner product (.,.)
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paper_title: Active vibration control during deployment of space structures

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Abstract Active vibration control during deployment of the NASA Solar Array Flight Experiment (SAFE) structure is considered in this study. The equations of motion of the SAFE structure are derived using Hamilton's principle. The approach to damp out the deployment-induced vibration is to use a force actuator located at the tip of the structure. Two different control strategies are investigated. In the first, the deployment-induced vibration is actively controlled from 70% to 100% deployment. In the second, the force actuator is turned on for a short period of time when the deployment reaches 70% and 100%. Both strategies make use of the linear regulator theory with a prescribed degree of stability. Simulated results presented show that both strategies damp out the deployment-induced vibration effectively. However, the second control system is simpler to design and implement and is, therefore, a more practical choice.
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paper_title: Active Vibration Control of a Micro-Actuator for Hard Disk Drives using Self-Sensing Actuator

paper_content:

In this article, active vibration control of a micro-actuator for hard disk drives using self-sensing actuation is presented. The micro-actuators used in this article are a slider type and a suspension type. The self-sensing performance of the installing position is compared and evaluated. An assembly including these micro-actuators may not be able to sense some vibration of suspension modes. Feedback control results of direct velocity feedback and positive position feedback are presented. The feasibility of these self-sensing approaches as a vibration suppression control on the micro-actuator was verified. Using the slider type micro-actuator, the sway mode spike signal in power spectrum density was suppressed by 76% using the direct velocity feedback control, and by 60% using the positive position feedback control. Using the suspension type micro-actuator, the suspension second bending mode spike signal in power spectrum density was reduced by 74% using the direct velocity feedback control, and by 96% u...
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paper_title: A Combined Positive Position Feedback and Variable Structure Approach for Flexible Spacecraft under Input Nonlinearity

paper_content:

This paper is concerned with vibration control of a flexible spacecraft in the presence of parametric uncertainty/external disturbances as well as control input nonlinearity through distributed piezoelectric sensor/actuator technology. To satisfy pointing requirements and simultaneously suppress vibrations, two separate control loops are adopted. The first uses piezoceramics as sensors and actuators to actively suppress certain flexible modes by designing positive position feedback (PPF) compensators which add damping to the flexible structures in certain critical modes. The second feedback loop is designed based on an output feedback sliding mode control (OFSMC) design where control input nonlinearity is taken into consideration. Simulation studies for the proposed control strategy on a flexible spacecraft demonstrate the effectiveness of the proposed approach.
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paper_title: Experimental Robustness Study of Positive Position Feedback Control for Active Vibration Suppression

paper_content:

Abstract : POSITIVE position feedback (PPF) control was introduced by Goh and Caughey in 1985 to control vibrations of large exible space structures. A PPF controller has several distinguished advantagesas compared to then widely used velocity feedbackcontrol laws. It is insensitive to spillover, where contributions from unmodeled modes affect the control of the modes of interest. As a second-order low-pass lter, a PPF controller rolls off quickly at high frequencies and is well suited to controlling the lower modes of a structure with well separated modes. Because of these advantages, PPF controller along with smart materials, in particular PZT (lead zirconatetitanate) type of piezoelectricmaterial, has been applied to many exible systems to achieve active damping. The design of a PPF controller requires the natural frequency of a structure. In practice, the structuralnatural frequencymay not be known exactlyor itmay varywith time.When the frequencyused in thePPF controller is different from that of the structure, the performance of the PPF control will adversely affected. Despite that PPF control is widely researched in literature, robustness study of PPF control when natural frequency is inexactly known is not reported. This motivates the authors to conduct experimental study of robustness of PPF control in active vibration suppression of a smart exible structure.
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paper_title: Unifying theory of tapping-mode atomic-force microscopy

paper_content:

We propose a general method for describing tapping-mode atomic-force microscopy. The combined participation of attractive and repulsive interactions determines the multivalued nature of the resonance curve. This, in turn, implies the coexistence of two different stable oscillations for some excitation frequencies. The coexistence of two stable oscillations depends on the driving force and tip-surface separation. Increasing the driving force inhibits the low-amplitude oscillation state. Because resolution depends on the oscillation state, we propose that the absence of the low amplitude solution is responsible for the inconsistencies observed in high-resolution imaging of biomolecules.
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paper_title: Towards local electromechanical probing of cellular and biomolecular systems in a liquid environment

paper_content:

Electromechanical coupling is ubiquitous in biological systems, with examples ranging from simple piezoelectricity in calcified and connective tissues to voltage-gated ion channels, energy storage in mitochondria, and electromechanical activity in cardiac myocytes and outer hair cell stereocilia. Piezoresponse force microscopy (PFM) originally emerged as a technique to study electromechanical phenomena in ferroelectric materials, and in recent years has been employed to study a broad range of non-ferroelectric polar materials, including piezoelectric biomaterials. At the same time, the technique has been extended from ambient to liquid imaging on model ferroelectric systems. Here, we present results on local electromechanical probing of several model cellular and biomolecular systems, including insulin and lysozyme amyloid fibrils, breast adenocarcinoma cells, and bacteriorhodopsin in a liquid environment. The specific features of PFM operation in liquid are delineated and bottlenecks on the route towards nanometre-resolution electromechanical imaging of biological systems are identified.
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paper_title: Control of a Z-axis MEMS vibrational gyroscope

paper_content:

This paper describes the design of the control loops in a z-axis, MEMS vibrational gyroscope operating in a vacuum enclosure. In this device, a silicon mass is driven through electrostatic actuator so that it has a sinusoidal linear motion, with a controlled speed. The design of a suitable controller, capable of maintaining the required speed and with prescribed restoring capabilities after shocks is briefly described in the paper. Attached to the driving mass, a second mass, free to move in the direction orthogonal to the motion of the first mass, is subjected to a Coriolis force, proportional to the product of the first mass speed by z-axis rotational speed. The sensing of the Coriolis force and, in turn, of the z-axis rotational speed, is performed in closed loop fashion, with a 1-bit quantized actuation. The restoring force that brings the motion of the second mass to zero is equivalent to the output bit stream of a band-pass sigma-delta converter and contains the information of the Coriolis force. The design of this second control loop and a detailed analysis on the signal-to-noise ratio achievable with the proposed design is reported.
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paper_title: Quantitative measurement of tip-sample interactions in amplitude modulation atomic force microscopy

paper_content:

The author introduces an algorithm for the reconstruction of the tip-sample interactions in amplitude modulation atomic force microscopy (“tapping mode”). The method is based on the recording of amplitude and phase versus distance curves and allows the reconstruction of tip-sample force and energy dissipation as a function of the actual tip-sample distance. The proposed algorithm is verified by a numerical simulation and applied to a silicon sample in ambient conditions.
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paper_title: Active beam vibration control using PZT actuators

paper_content:

Abstract Smart materials of lead-zirconate-titanate (PZT) piezoelectric ceramics have attracted attention in recent years for active vibration control, acoustic noise suppression, health monitoring and damage assessment. We at McDonnell Douglas Aerospace have been studying these ceramics for use as sensors and actuators in various space and aircraft structures. In this paper, we will report results of a recent study on active vibration control using monomorph PZT actuators. The experiments were performed on thin aluminum cantilever beams. Collocated and non-collocated sensors and actuators were employed. Two control techniques: the classical velocity feedback and adaptive feedback controls, were investigated. We have obtained significant damping and broadband vibration attenuation of greater than 30 dB using the classical control with the single-input single-output feedback approach. A 24 dB reduction has also been achieved using the adaptive control with the multiple-input single-output approach. Detaile...
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paper_title: Iterative control of dynamics-coupling-caused errors in piezoscanners during high-speed AFM operation

paper_content:

This paper addresses the compensation of the dynamics-coupling effect in piezoscanners used for positioning in atomic force microscopes (AFMs). Piezoscanners are used to position the AFM probe, relative to the sample, both parallel to the sample surface (x and y axes) and perpendicular to the sample surface (z axis). In this paper, we show that dynamics-coupling from the scan axes (x and y axes) to the perpendicular z axis can generate significant positioning errors during high-speed AFM operation, i.e., when the sample is scanned at high speed. We use an inversion-based iterative control approach to compensate for this dynamics-coupling effect. Convergence of the iterative approach is investigated and experimental results show that the dynamics-coupling-caused error can be reduced, close to the noise level, using the proposed approach. Thus, the main contribution of this paper is the development of an approach to substantially reduce the dynamics-coupling-caused error and thereby, to enable high-speed AFM operation.
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paper_title: Stability criterions of an oscillating tip-cantilever system in dynamic force microscopy

paper_content:

Abstract:This work is a theoretical investigation of the stability of the non-linear behavior of an oscillating tip-cantilever system used in dynamic force microscopy. Stability criterions are derived that may help to a better understanding of the instabilities that may appear in the dynamic modes, Tapping and NC-AFM, when the tip is close to a surface. A variational principle allows to get the temporal dependence of the equations of motion of the oscillator as a function of the non-linear coupling term. These equations are the basis for the analysis of the stability. One find that the branch associated to frequencies larger than the resonance is always stable whereas the branch associated to frequencies smaller than the resonance exhibits two stable domains and one unstable. This feature allows to re-interpret the instabilities appearing in Tapping mode and may help to understand the reason why the NC-AFM mode is stable.
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paper_title: Adaptive control of a MEMS gyroscope using Lyapunov methods

paper_content:

Two adaptive controllers for a vibrational MEMS gyroscope are described. Both controllers tune the drive axis natural frequency to a preselected frequency, regulate the amplitude of the drive axis vibration, cancel out quadrature error due to stiffness coupling, and drive the sense axis vibration to zero for force-to-rebalance operation. The first controller is based on an averaged, low frequency model, and the second is based on the full gyroscope model. Both controllers are successfully simulated for the Berkeley Z-axis gyro. The Lyapunov function used is critical in obtaining a good transient response, especially for the force-to-rebalance and automatic gain control loops. To implement the full model controller with displacement measurements only, and no velocity measurements, the controller is approximated.
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paper_title: Quantitative determination of contact stiffness using atomic force acoustic microscopy

paper_content:

Atomic force acoustic microscopy is a near-field technique which combines the ability of ultrasonics to image elastic properties with the high lateral resolution of scanning probe microscopes. We present a technique to measure the contact stiffness and the Young's modulus of sample surfaces quantitatively, with a resolution of approximately 20 nm, exploiting the contact resonance frequencies of standard cantilevers used in atomic force microscopy. The Young's modulus of nanocrystalline ferrite films has been measured as a function of oxidation temperature. Furthermore, images showing the domain structure of piezoelectric lead zirconate titanate ceramics have been taken.
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paper_title: Sliding mode control of a simulated MEMS gyroscope

paper_content:

The micro electro mechanical systems (MEMS) are penetrating more and more into measurement and control problems because of their small size, low cost, and low power consumption. The vibrating gyroscope is one of those MEMS devices that have significant impact on the stability control systems in transportation industry. This paper studies the design and control of a vibrating gyroscope. The device has been constructed in Pro-E environment and its model has been simulated in finite element domain in order to approximate its dynamic characteristics with a lumped model. A model reference adaptive feedback controller and the sliding mode controller have been considered to guarantee the stability of the device. It is shown that the sliding mode controller of the vibrating proof mass results in better estimate of the unknown angular velocity than that of the model reference adaptive feedback controller.
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paper_title: Vibration control in a composite box beam with piezoelectric actuators

paper_content:

This work presents a theoretical and experimental investigation of vibration control of composite box beams using distributed, surface mounted piezoelectric (PZT) patches as actuators. The finite element modeling of the box beam is done by formulating a first-order shear deformable active composite thin walled beam element. The degrees of freedom at each node are axial, bending in spanwise and chordwise directions, corresponding shears and twist. The superconvergent element derived uses higher order interpolating polynomials obtained by solving electromechanically coupled static governing differential equations. The open loop response is validated with experimental and analytical results available in the current literature. A system equivalent reduction expansion process (SEREP) is implemented for reduced order modeling. Open and closed loop responses to electrical bending actuation are obtained both experimentally and analytically using state space modeling. A proportional-integral (PI) controller using acceleration feedback is implemented for control of vibration due to single-frequency excitations. Experimental and numerical results correlate very well in the above cases. Eigenstructure assignment through output feedback is designed for multimodal control of transient responses.
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paper_title: Vibration suppression of distributed parameter flexible structures by Integral Consensus Control

paper_content:

Abstract Integral Consensus Control (ICC) is proposed and implemented in this paper for the first time, as a novel approach for vibration control in distributed parameter flexible structures. The ICC consists of multiple parallel first-order lossy integrators, with the goal of targeting all major participating resonant modes in the oscillation of the structure. The vibration control design is taken to a different level, by integrating the concept of consensus control design into the new dynamics. Each control patch on the flexible structure is considered as a node of a network, and a communication topology with consensus control terms are augmented in the controller design dynamics. The result is an effective vibration controller, which is also robust to failures and inconsistencies in the control system. A cantilever is used as a sample flexible structure to investigate the control method. Multi-agent representation of the system, state estimator dynamics and the ICC model are designed for the structure. Extensive numerical simulations have been conducted to show the suppression performance of the ICC under different input disturbances. A comparative study is presented to show the advantage of the decentralized design over the conventional centralized approach. The new consensus control design provides new possibilities to vibration control problems, where an effective, robust and synchronized suppression is needed.
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paper_title: Consensus positive position feedback control for vibration attenuation of smart structures

paper_content:

This paper presents a new network-based approach for active vibration control in smart structures. In this approach, a network with known topology connects collocated actuator/sensor elements of the smart structure to one another. Each of these actuators/sensors, i.e., agent or node, is enhanced by a separate multi-mode positive position feedback (PPF) controller. The decentralized PPF controlled agents collaborate with each other in the designed network, under a certain consensus dynamics. The consensus constraint forces neighboring agents to cooperate with each other such that the disagreement between the time-domain actuation of the agents is driven to zero. The controller output of each agent is calculated using state-space variables; hence, optimal state estimators are designed first for the proposed observer-based consensus PPF control. The consensus controller is numerically investigated for a flexible smart structure, i.e., a thin aluminum beam that is clamped at its both ends. Results demonstrate that the consensus law successfully imposes synchronization between the independently controlled agents, as the disagreements between the decentralized PPF controller variables converge to zero in a short time. The new consensus PPF controller brings extra robustness to vibration suppression in smart structures, where malfunctions of an agent can be compensated for by referencing the neighboring agents' performance. This is demonstrated in the results by comparing the new controller with former centralized PPF approach.
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paper_title: A general dynamics and control model of a class of multi-DOF manipulators for active vibration control

paper_content:

Abstract A general dynamic model of a class of parallel platforms for vibration control applications based on Kane's method is presented. A general parallel platform is composed of a moving platform, a base platform, and i limbs with identical kinematic structure. Each limb connects the mobile platform to the base platform by j + 1 hinges and j struts, where the prismatic actuator is fixed at one of the struts. The hinges can be replaced by any other kind of conventional hinges or flexure hinges. The control system architecture based on mixed H 2 /H ∞ synthesis method is introduced for a class of parallel platforms as a multiple-input/multiple-output (MIMO) problem for the purpose of active vibration isolation. A case study is illustrated and the theoretical analysis is validated at last.
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paper_title: Model-Based Multi-input, Multi-output Supervisory Semi-active Nonlinear Fuzzy Controller

paper_content:

: The authors recently proposed a new multi-input, single-output (MISO) semi-active fuzzy controller for vibration control of seismically excited small-scale buildings. In this article, the previously proposed MISO control system is advanced to a multi-input, multi-output (MIMO) control system through integration of a set of model-based fuzzy controllers that are formulated in terms of linear matrix inequalities (LMIs) such that the global asymptotical stability is guaranteed and the performance on transient responses is also satisfied. The set of model-based fuzzy controllers is divided into two groups: lower level controllers and a higher level coordinator. The lower level fuzzy controllers are designed using acceleration and drift responses; while velocity information is used for the higher level controller. To demonstrate the effectiveness of the proposed approach, an eight-story building structure employing magnetorheological (MR) dampers is studied. It is demonstrated from comparison of the uncontrolled and semi-active controlled responses that the proposed design framework is effective in vibration reduction of a building structure equipped with MR dampers.
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paper_title: Two-Degree-of-Freedom Active Vibration Control of a Prototyped “Smart” Rotor

paper_content:

This paper studies the load reduction potential of a prototyped “smart” rotor. This is, a rotor where the blades are equipped with a number of control devices that locally change the lift profile on the blade, combined with appropriate sensors and controllers. Experimental models, using dedicated system identification techniques, are developed of a scaled rotating two-bladed “smart” rotor of which each blade is equipped with trailing-edge flaps and strain sensors. A feedback controller based on H∞-loop shaping combined with a fixed-structure feedforward control are designed that minimizes the root bending moment in the flapping direction of the two blades. We evaluated the performance using a number of different realistic load scenarios. We show that with appropriate control techniques the variance of the load signals can be reduced up to 90%.
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paper_title: Novel Approach of Self-Sensing Actuation for Active Vibration Control

paper_content:

In a self-sensing actuator, the same piezoelectric element functions as both a sensor and an actuator. Due to their advantages of reducing the number of needed piezoelectric elements and true collocation of sensors and actuators, self-sensing actuators have attracted the attention of many researchers and many studies have been reported. Since the actuator signal and the sensor signal are mixed together in a self-sensing actuator, usually a bridge circuit is used to separate the two signals. It has been found that the two signals cannot be separate ideally, because the bridge is difficult to balance and the actuator signal is much larger than the sensor signal. In this study, the influence of the local strain on the output signal of a piezoelectric sensor is investigated numerically and experimentally. In order to delete the influence of local strain on performance of the self-sensing actuator, a new method using neural network is proposed to identify the strain of global vibration. The identified signal i...
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paper_title: Active vibration control using a novel three-DOF precision micro-stage

paper_content:

In this paper, we present an active vibration control system which is constructed based on a novel three-degrees-of-freedom (DOF) precision micro-stage. Unlike the traditional tripod systems, the proposed micro-stage is established to guarantee the compactness (60 mm(h) × 160 mm(d)) and the simplicity of its structure as well as the appropriate vertical/horizontal stiffness and the repeatability, which are essential in achieving the accuracy of sub-micrometers. First, combined with a finite element method (FEM), a physical model for the proposed micro-stage is constructed and its physical parameters, such as stiffness and damping coefficients, are estimated to predict the experimental results with high fidelity. In order to overcome the dynamic variations naturally stemming from the payload as well as the parameter uncertainties, a robust control system is then proposed to efficiently mitigate the vibration with a scale of sub-micrometers. Compared to the conventional control strategy, the proposed robust control scheme successfully establishes the active vibration control system and its performance is examined and validated through extensive experiments.
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paper_title: Robust control of a novel active pneumatic vibration isolator through floor vibration observer

paper_content:

Active vibration control techniques have been widely applied to enhance passive vibration isolators. The active strategy can improve the common disadvantages of the passive pneumatic isolator, such as resonant character and poor isolation performance at low frequency. In the study, a novel active pneumatic vibration isolator is designed. The isolator uses a passive isolator to support the weight of the payload and a pneumatic actuator to suppress the vibration disturbance through active control strategy. This investigation proposes a robust H∞ controller in order to have good disturbance rejection ability and robustness. According to the linearized nominal plant and appropriate weighting functions, the robust controller can be obtained and implemented by measuring vibration of payload and disturbance. However, it costs higher in practical implementation because two precision accelerometers must be used to measure the vibration at the same time. Therefore, the proportional integral observer (PI observer) i...
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paper_title: Modeling and High Dynamic Compensating the Rate-Dependent Hysteresis of Piezoelectric Actuators via a Novel Modified Inverse Preisach Model

paper_content:

Hysteresis of a piezoelectric actuator is rate-dependent, but most hysteresis models are based on elementary rate-independent models, which are not suitable for modeling actuator behavior across a wide range of frequencies. This paper presents a novel modified inverse Preisach model to compensate the hysteresis of a piezoelectric actuator at varying frequency ranges. The classical Preisach model for hysteresis is introduced first, the identification of μ-function through least square method is conducted afterwards. The linearity property of the Preisach model is analyzed and verified by experiment. A novel modified inverse Preisach model featured with weighed sum of μ-density functions is proposed, which is based on the linearity property. The fast Fourier transform method is adopted to select the proper μ-density functions and weights to form a real-time online rate-dependent compensator for piezoceramic (PZTs) hysteresis. During experiments with tracking multifrequency composed signals, we have observed that the hysteresis features of the PZT can be consistently compensated. The experimental results show that the proposed open-loop hysteresis adjust method greatly improves the tracking control accuracy of the PZT.
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Title: A Review on Recent Active Vibration Control Techniques

Section 1: Introduction
Description 1: Provide an overview of the importance of active vibration control, the challenges faced across different systems, and the scope of the review.

Section 2: Integral-Based Controllers
Description 2: Discuss integral-based controllers, including their structure, effectiveness, and examples from recent studies.

Section 3: Sliding Mode Control and Nonlinear Methods
Description 3: Explain sliding mode control and various nonlinear methods, highlighting their applications and effectiveness in different scenarios.

Section 4: Positive Position Feedback (PPF)
Description 4: Explore the use of Positive Position Feedback (PPF) in vibration control, particularly in space structures, and its various modifications.

Section 5: Vibration Control in MEMS Systems
Description 5: Review techniques specifically designed for vibration control in Micro-Electro-Mechanical Systems (MEMS), including applications and challenges.

Section 6: Other Novel Control Techniques
Description 6: Present other innovative and unconventional vibration control techniques, and their applications across different types of systems.

Section 7: Conclusion
Description 7: Summarize the main findings from the review, emphasizing the importance of understanding the specific vibration control challenge before selecting or designing a controller.