Pseudo‐active actuators: A concept analysis

A narrowband active vibration control algorithm with frequency estimator based on lattice notch filter is proposed to suppress the primary signal with multi line spectra. A adaptive iir (infinite impulse response) lattice gradient notch filter was adapted to estimated the frequency of the multi-harmonics buried in the primary signal, then the reference signal is filtered by the adaptive band pass filter. With the reference signal filtered by the adaptive band pass filter, active control algorithm is implemented. Simulations of the frequency estimation of the multi-sinusoidal signal are conducted and simulation results confirm that the proposed algorithm could achieve effective performance when the frequency of the primary disturbance is unknown. Active control of vibration has finds a lot application such as fans, engines, and air conditioners in nowadays. The basic concept of active vibration control is to suppress the primary disturbance with the secondary force which is of same amplitude and opposite phase. Signals generated by the rotating machines such as fans, diesel engines, and air conditioners is characterized with discreet frequency which cause damage to operator in the working environment. Narrowband active vibration control (NAVC) is an effective method to suppress such vibration with multi-line spectra. The application of NAVC has been implemented taken into applications since 1970's. A lot of algorithms have been proposed for suppress the primary disturbance with multi-spectral. There exists two families of algorithm in AVC system, which composed of filtered-X least mean square (FXLMS) algorithm and filtered-X recursive least square algorithm (FXRLS). Due to its simplicity and implementation efficiency, FXLMS algorithm is the most popular adaptive algorithm to suppress the primary disturbance compared to FXRLS algorithms. In the application of NAVC systems, the performance of NAVC systems is directly correlated with the reference signal and the primary signal. NAVC algorithm could not achieve effective performance if the correlation between the primary signal and the reference signal is weak. Frequency estimation of the primary signal is an effective method to adapt to improve the relativity between the reference signal and the primary signal. To estimate the frequency of a sinusoidal signal, a number of algorithm has been proposed to exploit the predictable nature of sinusoidal primary disturbance and characterize the frequency of the sinusoidal primary disturbance, such the Kalman algorithm, music, FFT (fast Fourier transform), etc. such method could be capable of tracking nonstationary or slowly-varyin g primary signals. However, they have some shortcomings in the application of NAVC systems. a lot of Kalman-based algorithms have been proposed for the frequency estimation of the sinusoidal signal in many applications such as the electrical power system, however, it requires much more computation burdens which is much more complicated compared the other algorithms. FFT methods have been proposed in the past to estimated the frequency of the primary signal, but it is has been found that the estimated result could not be accessed effectively in real-time of AVC system. Adaptive notch filter has been proposed for the frequency estimation of the sinusoidal signal in a lot of applications. Adaptive lattice filter shows much more stability and performance compared to the bilinear adaptive notch filter. In this paper, the adaptive lattice notch filter is introduced into an adaptive vibration control system to estimate the frequency of synthesized desired signal. Then, the reference signal is generated to suppress the primary vibration in the active vibration control system.

Commercial active noise and vibration control systems for vehicles are gradually developing, mainly in Japan, for both active noise control of interior sound and active control engine mounts [1]. There have been four Japanese commercial applications: • Active control for booming noise by Nissan in 1991, • Active vibration mount for idle noise and vibration by Toyota in 1997, • Active vibration mount for diesel engines by Nissan in 1998, • Active control for low-frequency road noise by Honda in 2000. Other manufacturers have, of course, developed similar systems, but these have not progressed to production applications. Additionally, active control engine mufflers using cancelling loudspeakers have been successfully demonstrated. A new type of active muffler, using a controlled oscillating butterfly valve in the exhaust line has been developed recently. The future of active control in vehicles is dependent on customers who are willing to pay the higher price for additional noise and vibration control, so that cost reductions are the essential factor in further commercial products. Trends towards fuel efficiency and lighter vehicles run counter to reducing noise and vibration. This has given new interest in active noise control and active control engine mounts as a solution to these conflicting issues.

The dynamic response and active vibration control of flexible composite material barrel under moving projectile are studied in this paper. After analyzing its vibration characteristics, the active vibration control technology is introduced to suppress its vibration. Combining theoretical modeling and experimental developing, some key problems of applying the active vibration control technology to vibration control of flexible composite barrel are discussed, which provides the technology foundation for later developing of flexible smart composite barrel. The coupling vibration model between the moving projectile and flexible composite barrel is established and solved by applying numerical iterative method and simulation experimental study, and many valuable conclusions are made. Besides, the dynamic response model and state space model for active vibration control of barrel under a moving projectile is established. And the adaptive fuzzy control strategy is introduced to suppress the flexible composite material barrel vibration. The testing system of dynamic response and active vibration control for barrel under a moving projectile is designed and developed. The experimental results showed the effectiveness of this kind of control strategy for flexible composite material barrel bonded with piezoelectric self-sensing actuator under a moving projectile, which demonstrated that using the smart material could suppress the time-varying system flexible structure vibration active control.

Macro fiber composite (MFC) has been widely investigated in the active vibration control. Yet, the actuation performance of MFC is a function of temperature. For the active vibration control system using MFC based on the linear piezoelectric equation, if the actuation parameters of MFC are variable, it is easy to cause insufficient control force or control spillover, which degrades the performance of control system. Therefore, an adaptive gain adjustment approach for the active vibration control system is developed, which ensures that the active control system can maintain the expected performance of vibration suppression under the time-varying ambient temperatures. The variation of actuation performance of MFC with temperature is measured by the experiment. The polynomial fitting method is utilized to obtain the functional relationship between the regulator parameters and ambient temperature. The performance of the proposed adaptive gain regulator is verified by the experiment in the temperature environment chamber. In the experiment, a scaled vertical tail model attaching the MFC actuator is as an example, and the fractional order positive position feedback control system is as a representative of the control system without temperature adaptability. When the temperature is −60°C, compared with the control system without regulator, the reduction ratio of response RMS of the control system with adaptive gain regulator is increased by 17.26%.The results indicate that the proposed adaptive gain regulator can avoid the adverse influence of the time.varying ambient temperature on the performance of the control system.

Active control of vibrations can outperform passive systems in certain applications, e.g. when broadband damping is requested or when several orders of a periodic disturbance have to be cancelled. To generate dynamic forces for the active control system, inertial mass actuators are frequently used. Mainly, they comprise a force generating element driving a single-degree-of-freedom oscillator which is coupled to the structure to be controlled. Thus, those actuators can also be used for retrofitting of existing structures or for prototyping purposes. In this paper, a design for an inertial mass actuator utilizing piezoceramic actuators is studied. Since those actuators integrate both stiffness and force generation into one element, this enables more compact and mechanically robust designs. With respect to the future integration into industrial applications, standard multilayer piezoelectric actuators are considered to decrease the costs of the system and allow for a high reliability. Usually, an inertial mass actuator should possess a low resonance frequency in order to enable operation over a broad frequency range. Since the stiffness of piezoelectric multilayer actuators is rather high, a lever mechanism is designed which transforms the stiffness of the piezoelectric element into the desired range. An analytical model of the inertial mass actuator is derived and parameter studies are performed to investigate the characteristics of the design. A prototype is set up and the main parameters like resonance and block force are experimentally validated. Finally, the integration of the actuator into an active vibration control system for a lightweight structure is described.

Vibration control strategies strive to reduce the effect of harmful vibrations such as machining chatter. In general, these strategies are classified as passive or active. While passive vibration control techniques are generally less complex, there is a limit to their effectiveness. Active vibration control strategies, which work by providing an additional energy supply to vibration systems, on the other hand, require more complex algorithms but can be very effective. In this work, a novel artificial neural network-based active vibration control system has been developed. The developed system can detect the sinusoidal vibration component with the highest power and suppress it in one control cycle, and in subsequent cycles, sinusoidal signals with the next highest power will be suppressed. With artificial neural networks trained to cover enough frequency and amplitude ranges, most of the original vibration can be suppressed. The efficiency of the proposed methodology has been verified experimentally in the vibration control of a cantilever beam. Artificial neural networks can be trained automatically for updated time delays in the system when necessary. Experimental results show that the developed active vibration control system is real time, adaptable, robust, effective and easy to be implemented. Finally, an experimental setup of chatter suppression for a lathe has been successfully implemented, and the successful techniques used in the previous artificial neural network-based active vibration control system have been utilized for active chatter suppression in turning.

This paper deals with the experimental assessment of the vibration suppression of the smart structures. First, we have presented a new high-speed active control system using the DSP320C6713 microprocessor. A peripheral system developed is composed of a data acquisition system, A/D and D/A converters, piezoelectric (PZT) actuator/sensors, and drivers for fast data processing. Next, we have tested the processing time of the peripheral devices, and provided the corresponding test results. Since fast data processing is very important in the active vibration control of the structures, we have focused on achieving the fast loop times of the control system. Finally, numerous experiments were carried out on the aluminum plate to validate the superior performance of the vibration control system at different control loop times.

Considering the problems of model uncertainties, higher harmonics, uncertain boundary conditions, external excitations, and system time delay in practical vibration control system, a novel active vibration control method is proposed to suppress the vibration of a thin plate structure with acceleration sensor and piezoelectric bimorph actuator in this paper. First, a nonlinear extended state observer (NESO)-based controller is designed to ensure the anti-disturbance performance of the structural vibration control system. Then, an enhanced differentiator-based time delay compensation method is introduced to improve the vibration suppression performance of the NESO-based controller. A real time hardware-in-the-loop benchmark for an all-clamped piezoelectric thin plate is designed to verify and compare the performance of the developed controller against conventional ESO-based methods (linear ESO with/without time delay compensation, NESO without time compensation). The best vibration suppression and disturbance rejection performance of the proposed NESO-based controller with an enhanced time delay compensator is verified in the comparative experimental results. This work is able to provide practitioners with vital guidance in designing active vibration control system in the presence of disturbances and time delay.

Active vibration control is introduced to an electrodynamic regenerative vibration damper. It is intended to improve vibration reduction capability using the regenerated energy. An electrodynamic actuator is used as an energy regenerative damper and active control actuator. This idea is applied to a moving mass type vibration absorber and vibration control is performed. In the case of energy regenerative control, a PWM step-up chopper is used to solve the dead zone problem. Active control signal is also controlled by other PWM chopper from the power supply. However, energy regenerative and active control mode can not operate at the same time. A new control law is introduced to switch control mode and to follow the ideal force. The ideal force is calculated using the LQ control theory. Experimental setup is mode to confirm the proposed technique and the damping capability is tested.

Active vibration control of large flexible space structure is a challenging topic in the system dynamics and control of spacecraft. This paper proposes a novel approach for vibration control on a large hoop truss structure, typically used as mesh satellite antenna. First, to suppress the first-order bending modal response of the hoop truss structure with an initial disturbance, a piezoelectric bending actuator with excellent bending actuation performance was carefully designed as a key component of an active vibration control system. Then, the actuating characteristics of the actuator and the dynamic equations of the active structure were analyzed and formulated based on a finite element method. In order to improve the vibration-attenuating effect of the control system, a Mamdani-type fuzzy logic algorithm was employed in a closed-loop control system. Finally, simulations and experiments were implemented to validate the effectiveness of the proposed active control approach and structure. The experimental results showed that the decay time of first-order bending modal response (around 0.34 Hz) of control system reduces by 75% compared with that of the uncontrolled system. The results demonstrate that the proposed active vibration control system has good application potential in controlling the bending modes of a large flexible spacecraft.

High-precision in-orbit missions, such as deep space exploration, communication, and Earth observation, have raised higher requirements for spacecraft microvibration suppression (MVS). The complex microvibration environment on spacecraft results in microvibration signals appearing as a combination of broadband random vibration and multiharmonic vibration, posing challenges to MVS. In this article, a new Volterra filtering-based hybrid active vibration control (NVHAVC) system is proposed for suppressing complex microvibrations in spacecraft. In the proposed NVHAVC system, a modified generalized soft-root-sign (MGSRS) adaptive algorithm is used to replace the least-mean-square adaptive algorithm in the filtered-x adaptive controller to address the impact of non-Gaussian or impulse noise on the MVS performance. And the MGSRS and Volterra filtering are introduced into both the broadband subsystem and narrowband subsystem for improving the MVS performance. Meanwhile, a frequency estimation algorithm based on an extended Kalman filter (EKF) is also introduced into the narrowband subsystem to improve the MVS performance of multiharmonic vibration with unknown time-varying frequency and amplitude. In addition, the physical output of the narrowband subsystem is reconstructed in the NVHAVC system framework to reduce the decrease of MVS performance caused by the same error feedback in both the broadband subsystem and the narrowband subsystem of the traditional hybrid active vibration control (AVC) system. Numerical simulation and experimental verification are conducted to validate the effectiveness of the proposed NVHAVC system. The results show that the improved broadband and narrowband subsystems can realize the MVS performance improvements of approximately 5–8 dB and 24–26 dB, respectively, compared with the traditional broadband and narrowband subsystems. The proposed NVHAVC system can achieve microvibration performance improvement of approximately 10 dB compared with the traditional hybrid AVC (HAVC) system.

Considering the number of applications, and the quantity of research conducted over the past few decades, it would not be an overstatement to label the piezoelectric materials as the cream of the crop of the smart materials. Among the various smart materials, the piezoelectric materials have emerged as the most researched material for practical applications. They owe it to a few key factors like low cost, large frequency bandwidth of operation, availability in many forms, and the simplicity offered in handling and implementation. For piezoelectric materials, from an application standpoint, the area of active control of vibration, noise, and flow, stands, alongside energy harvesting, as the most researched field. Over the past three decades, several authors have used piezoelectric materials as sensors and actuators, to (i) actively control structural vibrations, noise and aeroelastic flutter, (ii) actively reduce buffeting, and (iii) regulate the separation of flows. These studies are spread over several engineering disciplines—starting from large space structures, to civil structures, to helicopters and airplanes, to computer hard disk drives. This review is an attempt to concise the progress made in all these fields by exclusively highlighting the application of the piezoelectric material. The research carried out in the past five years, in the areas of modeling, and optimal positioning of piezoelectric actuators/sensors, for active vibration control (AVC), are covered. Along with this, investigations into different control algorithms, for the piezoelectric based AVC, are also reviewed. Studies reporting the use of piezoelectric modal filtering and self sensing actuators, for AVC, are also surveyed. Additionally, research on semi-AVC techniques like the synchronized switched damping (on elements like resistor, inductor, voltage source, negative capacitor) has also been covered.

From a control point of view, active vibration control requires attenuation of unknown and/or time varying multiple narrow band disturbances. Internal Model Principle (IMP) is currently used for building adaptive active vibration control systems. IMP leads to asymptotic suppression of the disturbances but often introduces in the case of multiple narrow band disturbances a strong ”water bed” effect on the output sensitivity function (unwanted amplification). In this paper, an indirect adaptive control methodology for attenuation of multiple unknown time varying narrow-band disturbances is proposed. The method is based on the real time estimation of the frequency of narrow-band disturbances using adaptive notch filters (ANF) followed by the design of a controller using adjustable band-stop filters (BSF) for the appropriate shaping of the output sensitivity function. A Youla-Kucera parametrization of the controller is used for reducing the computation load. This approach is compared on an active vibration control (AVC) system with the direct adaptive control scheme based on the internal model principle (IMP) proposed in [1]. Real time experimental results are provided.

In this paper, the characteristics of forces in active control systems connected to adjacent levels of a building are analyzed. The following characteristics are observed: (1) active control can provide significantly superior supplemental damping to a building, but causes a small frequency shift; (2) the linear quadratic regulator (LQR)-based control force is composed of an elastic restoring force component and a damping force component, where the damping force is almost identical to the total control force, however, the elastic restoring force is very small; and (3) the active control forces prevent motion most of the time during the entire control process. These three characteristics imply that active control systems connected to adjacent levels of a building behave like passive damping devices with adjustable parameters, namely damping characteristics in an active control, which is the mechanism used by semi-active control devices to reach similar performance as active control systems. Two indices are defined to quantify the damping characteristics of control forces in active control systems. These two indices can also be used to quantify the capacity of semi-active control to achieve the performance of active control. Based on the above observations, two principles are founded for optimization of parameters of semi-active control devices and passive dampers. The first is that the maximum output force of a semi-active or passive device to be designed is identical to an active device, called “design principle”. The other is the response equivalent principle, which states that the response of a building with semi-active or passive devices is the same as with active devices when the same maximum output force is applied. The design procedure for semi-active control devices and passive dampers is described in detail. Finally, numerical simulations of two benchmark problems is conducted to demonstrate the damping characteristics of active control and investigate the capacity of semi-active control to achieve the same performance as active control.

An integrated, compact piezohydraulic actuator system for active vibration control was designed and developed with a primary application for gas turbine aircraft engines. Copper tube was chosen as the transmission line material for ease of assembly. Liquid plastic, which meets incompressibility and low-viscosity requirements, was adjusted to provide optimal actuator performance. Variants of the liquid plastic have been prepared with desired properties between −40°F and 400°F. The effectiveness of this hybrid actuator for active vibration control (AVC) was demonstrated for suppressing critical speed vibration through two critical speeds for various levels of intentionally placed imbalance. A high-accuracy closed-loop simulation, which combines both finite element and state space methods, was applied for the closed-loop unbalance response simulation with/without AVC. Good correlation between the simulation and test results was achieved.