Active Vibration Isolation System Research Articles

Optimization of the on/off status configuration of control units in an active vibration isolation system—experiment

Active vibration isolation (AVI) is an important measure to attenuate vibration transmission in underwater vehicles and multiple active control units are usually used to attenuate low frequency vibrations induced by power equipment. Under certain operation conditions, however, the pre-installed control units in an AVI system may be redundant. Hence, it is necessary to optimize the on/off status configuration of all the control units. An optimization approach is proposed for configuration optimization of control units and validated by experiments. The criterion of the proposed approach is derived from the vibration responses of the monitoring points. The involved optimization, formulated as a constrained 0–1 nonlinear programming problem, utilizes the on/off status of control units as the input variable and the number of active units as the constraint. Optimized configurations were obtained by solving the nonlinear programming problem and deployed to the experimental system. The test results have demonstrated that vibration of the monitoring points can be effectively suppressed by activating only a portion of control units, and the configurations corresponding to maximum vibration reduction vary with different excitations.

Design of active vibration isolation system for satellite optical load based on Stewart platform

According to the requirements of hyperstatic environment of a satellite optical load during in orbit operation, the Stewart active vibration isolation platform was designed, and its dynamic equation was established by Newton Euler method. The virtual prototype model was established in ADAMS, and the accuracy of the model was verified by comparing the numerical solution and simulation solution of the modal frequency of the platform; On this basis, the dynamic model is decoupled into six SISO systems, and the optimal controller is designed for each subsystem. Finally, the whole system is simulated by ADAMS/MATLAB, and the displacement response curves of the load before and after control are obtained. The simulation results show that the Stewart active vibration isolation platform can effectively suppress the vibration.

Fuzzy algorithm-based active control method for vibration of a mechanical gear transmission system

The detached raft automatic frequency isolation system is a complicated system with high exceptionally nonlinear, high electromagnetic, and multi-source vibration modes. However, it generates a statistical method and it is hard to operate the organization. The fuzzy control algorithm, as an astute control method, can give a keen path to the active management of a complicated system of floating rafts. This study uses a system identification approach to construct mathematical models for a floating raft active vibration isolation system with discrete transfer work. The fuzzy model is used in tests and simulations controller is built using two contributions of acceleration and its variation, as well as a single result of control voltage. The control isolation system is a complicated system with many moving parts. A lot of moving parts profoundly nonlinear, high electromagnetic and multi-source vibration modes, generating a statistical method and it is hard to operate the organization. The fuzzy control algorithm, as a smart control method, can give a keen path to the active management of a sophisticated floating raft system. This research uses an identification strategy to construct a floating raft active vibration isolation technology discrete transfer work mathematical models. The fuzzy controller is then put together using two contributions: acceleration and variation, as well as a single outcome of control voltage for simulations and experiments research.

Flight test results for microgravity active vibration isolation system on-board Chinese Space Station

The Fluid Physics Research Rack (FPR) is a research platform employed on-board the Chinese Space Station for conducting microgravity fluid physics experiments. The research platform includes the Microgravity Active Vibration Isolation System (MAVIS) for isolating the FPR from disturbances arising from the space station itself. The MAVIS is a structural platform consisting of a stator and floater that are monitored and controlled with non-contact electromagnetic actuators, high-precision accelerometers, and displacement transducers. The stator is fixed to the FPR, while the floater serves as a vibration isolation platform supporting payloads, and is connected with the stator only with umbilicals that mainly comprise power and data cables. The controller was designed with a correction for the umbilical stiffness to minimize the effect of the umbilicals on the vibration isolation performance of the MAVIS. In-orbit test results of the FPR demonstrate that the MAVIS was able to achieve a microgravity level of 1–30 μg0 (where g0 = 9.80665 m ∙ s−2) in the frequency range of 0.01–125 Hz under the microgravity mode, and disturbances with a frequency greater than 2 Hz are attenuated by more than 10-fold. Under the vibration excitation mode, the MAVIS generated a minimum vibration acceleration of 0.4091 μg0 at a frequency of 0.00995 Hz and a maximum acceleration of 6253 μg0 at a frequency of 9.999 Hz. Therefore, the MAVIS provides a highly stable environment for conducting microgravity experiments, and promotes the development of microgravity fluid physics.

Self-tuning PID feedback control method for magnetic suspension active vibration isolation system with parameters uncertainty

A self-tuning PID (Proportion-Integral-Derivative) control method based on the adaptive mechanism was proposed for the magnetic suspension active vibration isolation system with the characteristics of nonlinear, time-varying, and model parameter uncertainty. The controller identified the controlled object parameters online and solved the controller parameters in real time. To test the effectiveness of the proposed method, a six degree-of-freedom (DOF) magnetic suspension active vibration isolation system was designed and built. The six DOF dynamic model of the vibration isolation system with uncertain model parameters was derived for control. Experiments were carried out and compared with the control effects of the tradition PID control and cascade PID control algorithm. The experimental results show that the proposed self-tuning PID controller has more outstanding practicality and effectiveness in solving the model parameter uncertainty problem compared with the existing studies at home and abroad, and it also proves that the control method has a good isolation effect on the wide band disturbances.

A novel 3-DOF active vibration isolation method for TBM’s laser target

In the process of full-face tunnel boring machine (TBM) tunneling, pitch angle measurement accuracy of the laser target is greatly reduced by low frequency vibrations with large amplitude and multiple degrees of freedom. In order to improve pitch angle measurement accuracy of laser target under vibration, a three-degree-of-freedom (3-DOF) active vibration isolation system is designed in this paper. A plate-type voice coil motor with large air gap and large thrust is designed based on genetic algorithm. In order to increase damping of the vibration isolation system, an eddy current damper is designed by combining copper plate and permanent magnet of the voice coil motor. An active vibration isolation device for laser target was built by using the designed plate-type voice coil motor and eddy current damper, and the dynamic model of the system was established. Aiming at control and stability problems caused by the nonlinear factors, a High-Frequency sliding mode controller which can ensure system asymptotically stable is designed in this paper. A 1–30 Hz sinusoidal sweep excitation experiment was performed on a shaking table. The experimental results show that the active vibration isolation system has a good damping effect. The root mean square (RMS) of acceleration in Y direction can be attenuated by 90.5%, in Z direction can be attenuated by 95.8%. The active isolation system effectively attenuates the vibration transmitted to the laser target, and pitch angular fluctuation of the laser target is reduced by 75.8%. The designed active vibration isolation system improves the pitch angle measurement accuracy of the laser target.

An adaptive feed-forward active vibration isolation algorithm for input disturbance unbalanced MIMO systems

Multi-axis active vibration isolation systems often encounter order-of-magnitude differences in the perturbations in each input direction. This causes adaptive feedforward control systems to converge at a relatively slow rate, or possibly even diverge. To solve this problem, we propose an improved adaptive feedforward vibration isolation technique based on the classical FxLMS algorithm. Our approach constructs a weighted transformation matrix based on singular value decomposition, attenuates the uneven influence of the input perturbations, and effectively avoids the problems of slow convergence and poor stability faced by existing adaptive algorithms. This paper first describes the parameter update algorithm and the structure of adaptive feedforward algorithms. The convergence of the proposed algorithm is then analyzed, and the method for constructing the weighting matrix is introduced. Finally, the feasibility of the algorithm is verified using a multi-axis vibration isolation system simulation model. The simulation results show that the power spectrum of acceleration in the frequency domain from 0.1 to 100 Hz is attenuated by up to 70 dB under the condition of no excitation in a specific direction, demonstrating the vibration isolation effect of the algorithm. The relative deviation between the predicted and actual parameter error is no more than 6 %, which shows that the algorithm achieves good convergence. The proposed algorithm has potential applications in the active vibration isolation of space telescopes and high-precision optical equipment.

An overview of the development of intelligent materials and active vibration isolation systems for vehicles

Intend to reduce the impact of external vibrations on the smoothness of automotive precision instruments and vehicles and to improve the operational accuracy of automotive precision instruments and the comfort of passenger vehicles, vibration isolation technologies are used and active control systems are applied to vibration isolation systems. The extensive use of smart materials in vibration isolation systems has enabled the design of vehicle structures based on smart materials to meet the suppression of vehicle vibrations well. This paper reviews the application of commonly used smart materials to the field of vehicle vibration damping, summarizes the configuration design of single-axis and multi-axis vibration isolation systems, and develops the thinking behind the application of active control technology to other carriers, pointing out the future research direction of current smart materials for vehicles.

Design and correlation analysis of quasi-zero stiffness passive vibration isolation air spring

Vibration isolation systems are widely used in high-end automobile manufacturing, precision instrument processing, building and bridge seismic resistance, ship machinery noise reduction and other engineering fields, with good development prospects. At present, the existing vibration isolation systems on the market are mainly divided into active and passive vibration isolation systems. Passive vibration isolation does not require external energy input. Its structure is simple and the control scheme is easy to implement. However, passive vibration isolation performs well in high frequency vibration but not in low frequency. As a new nonlinear low-frequency vibration isolation technology, the quasi-zero stiffness vibration isolation system has changed the traditional concept of linear system vibration isolation. In addition, compared with traditional spring, air spring as a new type of elastic vibration isolation mechanism has many excellent performances, such as high fatigue resistance and high stiffness. Therefore, this paper uses air spring to design a passive vibration isolation quasi-zero stiffness air spring structure with good vibration isolation effect, simple structure and low cost in both low-frequency and high-frequency vibration.

Investigation on active vibration isolation with multi-axis control: Analysis and experiment

Vibration isolators are usually used to attenuate the transmission of vibration of power machinery to the flexible foundation. Since vibration energy is transferred nearly through all the degrees of freedom of an isolator, it is difficult to guarantee sufficient vibration attenuation by the single-axis control at each active isolator. In order to enhance attenuation at each vibration isolator, a novel configuration of active vibration isolation is proposed. Each active isolator is composed of two rubber isolators and one intermediate rigid mass in which eight electromagnetic actuators and six error accelerometers are attached. Six control forces are applied on the intermediate mass to suppress its multi-axis vibration. Moreover, the weakened interaction between isolators allows independent local control at each isolator. A numerical model is established to verify the proposed active vibration isolation and the results show that the transmission of vibration from the source to the flexible hull structure can be nearly cut off when the error vibrations of each intermediate mass are attenuated completely. The effectiveness is also proved by an experimental active vibration isolation system and the proposed isolation configuration with multi-axis control can achieve more significant attenuation of vibration of the hull structure than the commonly used active vibration isolation with only single-axis control.

Adaptive neural control of microgravity active vibration isolation system subject to output constraint and unexpected disturbance

The objective of this investigation is to explore the issue of microgravity vibration isolation control within a space station, while considering constraints on output and unexpected disturbances. Drawing upon an analysis of the environment and operating conditions within the space station, the uncertainties resulting from variable payloads and unforeseen disturbances are depicted as combined disturbances. On this basis, an actor–critic neural network with energy consumption evaluation is used to estimate the combined disturbances and devise strategies for compensatory control. Furthermore, an adaptive robust term is devised to handle errors generated by the estimation process of the neural network. Additionally, to ensure that the output of the isolation system remains within specified bounds, an improved predefined performance function is introduced, thereby ensuring adherence to constraints regardless of initial conditions. Simulations conducted under different operational scenarios demonstrate the effectiveness of the proposed controller in achieving system stability. The results indicate a remarkable suppression of onboard vibration amplitude, amounting to approximately 60 dB within the frequency range of 2 to 100 Hz.

Переходные процессы в активной системе виброизоляции с инерционным компенсатором виброактивных сил

Transient processes were analyzed in the automatic control system of the vibroactive forces electrodynamic compensator. Active vibration isolation system was considered, where a pneumatic spring based on the rubber-cord shell and the vibroactive forces electrodynamic compensator with a hydraulic inertial motion transducer were combined in a single construct. The paper shows that to ensure high efficiency of the vibration isolation, the gain in the electrodynamic compensator control circuit should be sufficiently large, but this leads to an increase in the transient process and the oscillation period duration. The proportional-integral controller could be introduced to reduce the oscillation index in the control system. However, the inertial mass oscillation center is shifting in the electrodynamic compensator in this case, which could lead to losses in its performance. An approach to solving this problem is proposed using the mechanism of averaging the measured current in the control coil and subtracting it from the current value, which makes it possible to eliminate the inertial mass shift while maintaining the transient process short duration, when a proportional-integral controller is included in the control circuit. It is shown that reducing the transient process period due to inclusion of the proportional-integral controller in the control circuit significantly increases the vibration isolation efficiency in the vibroactive forces non-stationary mode, for example, in the start-stop mode.

Electromagnetic Design and Analysis of Inertial Mass Linear Actuator for Active Vibration Isolation System

Underwater radiated noise from anthropogenic structures must be reduced to protect the marine environment. Active vibration isolation that can reduce noise generated from vibration sources by providing counteracting forces can solve this issue. This paper presents a 120 N class electromagnetic inertial mass linear actuator for an active vibration control system in a large ship. The proposed actuator is operated based on the Lorentz force, also known as electromagnetic force. To achieve a high thrust force to weight ratio, a permanent magnet with outer radial magnetization is used. In order to design and analyze the proposed model, a simple magnetic equivalent circuit analysis was first conducted to achieve an appropriate force, and its value was compared and verified with the magnetostatic finite element method. The dynamic characteristics of the actuator were then evaluated, and the performance was analyzed at various operating frequency points. The bobbin housing supporting the coil causes an eddy current loss due to materials with electrical conductivity. As a result, the damping force is generated by the reduction in magnetic flux, and the control force tends to decrease.

An Active Vibration Isolation and Compensation System for Improving Optical Image Quality: Modeling and Experiment.

Optical detection equipment (ODE) is subjected to vibrations that hamper the quality of imaging. In this paper, an active vibration isolation and compensation system (VICS) for the ODE is developed and systematically studied to improve the optical imaging quality. An active vibration isolator for cameras is designed, employing a dual-loop control strategy with position compensation and integral force feedback (IFF) control, and establishing the mapping relationship between vibration and image quality. A performance metric for evaluating images is also proposed. Finally, an experimental platform is constructed to verify its effectiveness. Based on the experimental results, it can be concluded that the proposed VICS effectively isolates vibrations, resulting in a reduction of 13.95 dB in the peak at the natural frequency and an 11.76 Hz widening of the isolation bandwidth compared with the system without it. At the same time, the experiments demonstrate that the image performance metric value increases by 46.03% near the natural frequency.

Tracking-Differentiator-Based Position and Acceleration Feedback Control in Active Vibration Isolation with Electromagnetic Actuator

In order to improve the performance of the active vibration isolation system (AVIS) with electromagnetic actuator, several problems of vibration control are studied. Position control is a critical component in suspension systems, and the position sensor noise can extremely affect the stability of the system, so a tracking differentiator (TD) is proposed to obtain effective differential signal from relative position sensor. In vibration control, the feedback of acceleration combined with PD position feedback is presented to suppress transmission of periodic vibrations. Then, taking the acceleration transmission as the evaluation index, the acceleration transmission under the presented control method is derived, and the influence of control parameters on vibration isolation performance is discussed in detail. The vibration isolation performance is improved from 24.47 dB to 2.4 dB at resonance frequency, and −34 dB attenuation is achieved at 100 Hz with respect to vibration isolation mount system tested on the ground. The experimental results demonstrate that the performance of active vibration isolation system are improved by the proposed acceleration feedback control.

Research on an Active Vibration Isolation System with Hybrid Control Strategy for The Guidance System of TBM

Research on an Active Vibration Isolation System with Hybrid Control Strategy for The Guidance System of TBM

Implementation of structurally pre-stressed piezo actuator based active vibration isolation system for micro milling

This paper presents the implementation of a structurally pre-stressed piezo actuator based active vibration isolation system incorporated with tool based micromachining setup for analyzing and comparing the milled pocket depth surface before and after isolation. A carbide micro end mill tool with 1 mm diameter and 4 flutes has been used for carrying out pocket milling experiments with and without vibrations on copper work pieces having 3 mm thickness. The machining parameters selected were spindle speed of 16,000 rev/min with 64 mm/min feed rate and 50 μm depth of cut. Two sets of pocket milling experiments were carried out using the proposed vibration isolation setup one with vibration and the other without vibration. In the first set of experiment, the source actuator was actuated for generating vibrations during pocket milling whereas in the second set of experiment, both source and isolator actuators were actuated for nullifying the vibrations generated during pocket milling. The macroscopic lens output images of the pocket depth surfaces before and after isolation were then compared corresponding to various actuation voltages at different frequencies using the proposed vibration isolation setup. Based on the macroscopic lens output images it was observed that the milled pocket depth surface obtained by actuating only source actuator showed distinct rings wherein the ring count matched with frequency and feed rate that has been provided during machining. However, the milled pocket obtained by actuating both source and isolator actuators resulted in surface characteristics with less pronounced rings similar to that of regular machining. Also the rings that has been formed showed more defined edges with the increase in actuator voltage indicating that these distinct patterns were caused due to the vibrations generated by the source actuator alone and not other factors.

Design of Active Vibration Isolation Controller with Disturbance Observer-Based Linear Quadratic Regulator for Optical Reference Cavities

The optical reference cavity in an ultrastable laser is sensitive to vibrations; the microvibrations in a space platform affect the accuracy and stability of such lasers. In this study, an active vibration isolation controller is proposed to reduce the effect of vibrations on variations in the cavity length and improve the frequency stability of ultrastable lasers. Based on the decentralized control strategy, we designed a state-differential feedback controller with a linear quadratic regulator (LQR) and added a disturbance observer (DOB) to estimate the source noise. Experiments were conducted using an active vibration isolation system; the results verified the feasibility and performance of the designed controller. The accelerations along the axis (Z-, X-, Y-) directions were suppressed in the low-frequency band within 200 Hz, and the root-cumulative power spectral densities (PSDs) declined to 1.17 × 10-5, 7.16 × 10-6, and 8.76 × 10-6 g. This comprehensive vibration met the requirements of an ultrastable laser.

High Precision Hybrid Reluctance Actuator With Integrated Orientation Independent Zero Power Gravity Compensation

This article presents a novel method for enabling energy-efficient and orientation-independent gravity compensation in active vibration isolation systems by taking advantage of the inherent negative stiffness of a hybrid reluctance actuator (HRA). Counteracting the gravitational force acting on the mover of an HRA with the position dependent force of the actuator’s integrated permanent magnet, the gravitational force can be compensated without the need for an additional actuation. An HRA-system with two translational degrees of freedom (DOF) is developed, comprising a permanent magnet for generating a constant biasing flux for both system axes and two actuator coils per axis for actively controlling the position of the mover. The system prototype has an actuation range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pm$</tex-math></inline-formula> 0.7 mm in both DOF, while enabling energy efficient gravity compensation of payloads up to 500 g by an additional current feedback control loop. Experiments demonstrate that the current consumption for compensation of a 500 g payload is reduced from 1.58 A to 10 mA, which corresponds to a reduction of the power consumption by a factor of 25 000.

Active/passive vibration isolation with multi-axis transmission control: Analysis and experiment

It is necessary to cut off all vibration transmission paths for an active vibration isolation system. A greater suppression of local responses will result in a better overall attenuation. In order to realize impediment at possible transmission paths, a new scenario of multi-axis transmission control is proposed, in which the active/passive isolator attenuates vibration transmission at multi-degrees of freedom by vertical and horizontal actuators mounted orthogonally on the intermediate inertial mass. This scenario is able to weaken the cross-coupling of control action between isolators by the passive parts. In order to investigate the characteristics of multi-axis transmission control, the dynamic model of a partitioned isolation system with one active/passive isolator is established and the involved transmission control is analyzed. The numerical results show that the foundation vibration can be attenuated along with the decrease of vibrations of the intermediate inertial mass. It is further revealed by experimental results that the multi-axis transmission control at the intermediate inertial mass is necessary to achieve sufficient vibration attenuation in the foundation, whereas the control in a single axis is ineffective. These verified results imply that the active/passive isolation with local transmission path control makes it possible to apply decentralized control in a large active vibration isolation system.