Passive Vibration Isolation System Research Articles

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.

Experimental Study on the Active Control and Dynamic Characteristics of Electromagnetic Active–Passive Hybrid Vibration Isolation System

Targeting the problems of conventional active–passive hybrid vibration isolation systems, such as low output force, poor bearing capacity, large power loss and inability to withstand strong impacts, this paper proposes an active–passive hybrid vibration isolation system combining an electromagnetic actuator, rubber passive vibration isolator and magnetorheological damper. The overall design of the hybrid vibration isolation system is first introduced. Then, a two-dimensional electromagnetic frequency-domain simulation is carried out on the electromagnetic actuator to obtain the output characteristics. A three-dimensional modeling is conducted to simulate the electromagnetic–mechanical coupling in the time–frequency domain to obtain nephograms of the magnetic flux diffusion distribution and power loss. Then, a dynamic stiffness test is carried out on the rubber vibration isolator to obtain the dynamic stiffness characteristics and the damping angle curve. At the same time, an adaptive suppression filtered-x least mean square (ASFXLMS) algorithm is proposed to adjust the update of the control weight coefficients to ensure that the current signal does not exceed the effective operating range of the actuator when the electromagnetic actuator is subjected to strong external disturbances. Finally, a hybrid vibration isolation system-based active vibration isolation experimental platform is built, and multifrequency line spectra active–passive vibration isolation experiments are carried out. The results demonstrate that the hybrid vibration isolation system has good control effects in the time–frequency domain and shows good robustness when subjected to impact.

Passive Isolator Design and Vibration Damping of EO/IR Gimbal Used in UAVs

One of the most critical factors affecting the quality of the images captured by the surveillance systems used in the unmanned aerial vehicles is the vibrations transmitted from the aircraft to the gimbal. The gimbal used in unmanned aerial vehicles is essential equipment, holding the camera steadily and accurately and pointing it in the desired direction. Within the scope of this article, a passive vibration isolation system design has been made for the two-axis electro-optical gimbal used in the mini unmanned aerial vehicle. By choosing the spring-damper system among different methods, the design that isolates the harmonic vibration from the platform on a single axis has been made using the analytical method. The analytical method was used to create a design that isolates the harmonic vibration from the platform along a single axis. In addition, the part named 'Pan Yoke', which contains this damper system, was designed with a computer-aided design program, and natural frequency values were checked with Ansys modal analysis. The frequency of the vibration transmitted from the air vehicle to the gimbal and the natural frequency of the designed part have been determined to be close to each other, at around 200 Hz. The natural frequency values of this part were optimised with various design changes and topology optimisations to prevent the part from resonating.

Dynamic Research on Low-frequency Vibration Isolation Tables

In the paper, an establishment of dynamic characteristics of tabletops of the newly-developed optical tables is being discussed upon. Low-frequency vibration isolation systems are reviewed. Theoretical and experimental tests have been performed. Dynamic models of an optical table on a vibrating platform at different excitations have been developed, the dynamic displacement and the resonance frequencies of the system have been established and vibration transmissibility curves have been presented. The obtained dynamic characteristics of the mechanical passive low-frequency vibration isolation system show that such a system is able to isolate the vibrations effectively. The results of the performed experimental tests confirm the data of the theoretical research.

Design of a compliant lever-type passive vibration isolator with quasi-zero-stiffness mechanism

This paper focuses on design and analysis of a hybrid passive vibration isolation system that uses both compliant lever-type and quasi-zero-stiffness (QZS) mechanisms. By using the lever-type mechanism, an inertial coupling induced antiresonance frequency is generated and the effective mass of the system is increased, which improve low-frequency vibration isolation performance. The QZS mechanism is used to provide very low stiffness, which in turn lowers the resonance and antiresonance frequencies of the system. Hence, the lower limit of the isolation bandwidth can be significantly reduced. After examining the system analytically, a finite element model is formed. Finally, the design is manufactured and tested. The tests validate the analytical and numerical calculations, thereby confirming that lower limit of the isolation frequency range can be substantially decreased by adjusting the effective mass and the effective stiffness of the system.

Modeling and characteristics study of double-diamond bionic vibration isolation system with inerter

An integrated and bionic passive vibration isolation system is proposed based on the double-diamond bionic structure and inerter to solve the problems of poor low-frequency vibration isolation performance, narrow vibration isolation frequency band, and big additional mass of current passive vibration isolation system. To analyze the low-frequency vibration isolation performance and the valuable frequency band, the nonlinear dynamic model of the system is established, then the system transmission characteristics and stability are studied. It is found that the system can reduce the amplitudes of resonant peaks, broaden the valuable frequency band, and the system stability is excellent. Seen from the performance analysis, the introduction of the inerter with smaller additional mass makes the system have better vibration isolation performance and wider effective vibration isolation frequency band. The proposed system provides a new solution for vibration control in practical engineering.

Recent Advances in Quasi-Zero Stiffness Vibration Isolation Systems: An Overview and Future Possibilities

In recent decades, quasi-zero stiffness (QZS) vibration isolation systems with nonlinear characteristics have aroused widespread attention and strong research interest due to their enormous potential in low-frequency vibration isolation. This work comprehensively reviews recent research on QZS vibration isolators with a focus on the principle, structural design, and vibration isolation performance of various types of QZS vibration isolators. The negative-stiffness mechanism falls into two categories by different realization methods: passive and active/semi-active negative-stiffness mechanisms. Representative design, performance analysis, and practical application are elaborated for each category. The results show that passive vibration isolation systems have excellent low-frequency vibration isolation performance under specific payload and design parameters, whereas active/semi-active vibration isolation systems can better adapt to different environmental conditions. Finally, the development trends and challenges of QZS vibration isolators are summarized, and the solved and unsolved problems are highlighted. This review aims to give a comprehensive understanding of the QZS vibration isolation mechanism. It also provides guidance on designing new QZS vibration isolators for improving their vibration isolation performance and engineering applicability.

Experiment and analysis of active vibration isolation system based on rigid pedestal using SDOF actuator

This paper is about the active-passive isolation system based on single degree of freedom electromagnetic actuator and focuses on different control effect of different measure points. In view of this problem, the authors analyze the vibration characteristics of the active and passive vibration isolation systems of electromagnetic airbags under single and multi-vibration isolators. Then they decompose the rigid pedestal vibration into two orthogonal components, the vertical translation and the fix axis rotation. After that compare simulation and experiment results in terms of the control effect when the single active-passive isolator location varies. Finally, the authors draw a conclusion about the reason why the rigid pedestal vibration can be globally controlled by arranging more than 3 active-passive isolations and design a multiple isolator system experiment to verify.

Vibration Reduction in a Pulse Tube-Cooled High Purity Germanium Detector

High-purity germanium (HPGe) is a vibration-sensitive, high-resolution detector. It has been found that microphonic noise induced by vibration and electromagnetic interference from EMC causes energy resolution degradation in HPGe detectors. In this paper, to enhance the energy resolution of a pulse tube-cooled high purity germanium detector, a passive vibration isolation system for the portable pulse tube cooler (PTC) was employed and investigated. In order to evaluate the performance of the vibration isolation system, micro-vibration tests of the compressor with a vibration isolation kit and detector mounting interface were performed. Meanwhile, detector energy resolution and detector signal noise were tested, respectively, under the PTC, with the isolation system switched to either an on or off condition. The test results indicate that the effectiveness of passive vibration isolation techniques is confirmed, and no degradation was induced by PTC vibration on detector energy resolution.

Optimal Active Vibration Isolation System Design using Constrained H2 control.

Active vibration isolation systems can increase the performance over passive vibration isolation systems by mitigating the trade-off in sensitivity to direct and indirect disturbances. However, the potential performance improvement, as well as the optimal system design are not yet fully understood. This paper proposes an optimal system design method based on constrained H2 control and parametrized mechanics, where the disturbance spectra of the floor vibrations, actuator and sensing noise are explicitly taken into account. Using this method, the optimal system parameters, as well as the potential performance improvement can be quantified. This method is applied to a case study to show its usefulness. From this case study, and the thereby imposed constraints, it can be concluded that AVIS can significantly improve the performance for all considered direct disturbance powers.

A simple and efficient passive vibration isolation system for large loads in closed-cycle cryostats.

We present a system for passive damping of vibrations along three spatial degrees of freedom for cryostats equipped with closed-cycle coolers. The system, designed to isolate a payload of 30kg, consists of two stages of isolation for vibrations in the vertical direction. The first isolation stage incorporates a trapezoidal beryllium copper cantilever blade. The second stage is attached to the blade via a steel wire and consists of four extension springs with an extended length of 370mm. At 1.6K, the stages possess vertical resonance frequencies of 2.1 and 1.3Hz, respectively. The vertical length of the setup with a cumulative length of 580mm also acts as a pendulum with a resonance frequency of 0.65Hz. In the frequency band from 5 to 200Hz, the frequency-integrated acceleration decreased from 6.7 × 10-3 to 4.3 × 10-5 g along the horizontal direction and from 4.3 × 10-3 to 7.2 × 10-5 g along the vertical direction. This corresponds to a reduction in vibrations by factors of 156 and 60, respectively. Overall, we achieve a simple, robust, and cost-efficient vibration isolation system for upgrading standard-type cryostats.

High Damping Passive Launch Vibration Isolation System Using Superelastic SMA with Multilayered Viscous Lamina

Whole-spacecraft launch-vibration isolation systems are attractive for achieving the goal of better, faster, cheaper, and lighter small satellites by reducing the design-load and vibration-test specifications for on-board components. In this study, a three-axis passive launch-vibration isolation system, based on superelastic shape memory alloy (SMA) technology, was developed to significantly attenuate the dynamic launch loads transmitted to a small satellite. This provides a superior damping characteristic, achieved by superelastic SMA blades stiffened by multilayered thin plates with viscous lamina adhesive layers of acrylic tape. The basic characteristics of the proposed isolation system with various numbers of viscoelastic multilayers were obtained through a static load test. In addition, the effectiveness of the design was validated through a launch environment simulating sine and random vibration tests.

Применение параллелограммного механизма с эффектом квазинулевой жесткости в виброзащитных системах кресла оператора строительно-дорожной машины

For vibration protection of operators of construction and road machines, a promising direction is the use of passive vibration protection systems based on mechanisms with quasi-zero rigidity. Passive vibration isolation systems, being less complex than active ones, require less frequent maintenance, are cheaper to manufacture and more reliable than active ones. The problem of selecting the optimal, most reliable and simple design of the mechanism with the effect of quasi-zero rigidity remains urgent. In this case, the most widespread use of elements that create negative stiffness. This requires elements with positive stiffness in the mechanism, which complicates the design. More promising structures of mechanisms, where elements with negative stiffness are not separated into a separate structure. In mechanisms such as the parallelogram, studied in this work, a section with quasi-zero stiffness can be provided with just one tension spring, which simplifies the design and reduces the cost of the entire vibration protection system. By the method of direct analytical inference for the presented diagram of a parallelogram mechanism with one spring, analytical expressions are obtained for the tensile force of the spring necessary to compensate for the force of gravity of the chair with the operator on the height of the chair and the length of the spring. As an example, the graphical dependences of the spring tensile force on the chair lift and on the spring’s own length are given as an example. It was found that the static force characteristic of the spring is a straight line passing through the origin. That is, the zero force corresponds to the zero spring length, which is not technically feasible. It is proposed to use a mechanism that replaces the tension spring, which will provide a given power characteristic.

Vibration error compensation algorithm in the development of laser interference absolute gravimeters

Abstract. Measurement error arising from vibration interference is recognized as the primary obstacle limiting the accuracy and stability of laser interference absolute gravimeters. The present work addresses this issue by proposing a global search optimization algorithm that determines the optimal absolute value of gravity based on the measured time–displacement coordinates of a falling body and the signal obtained from the passive vibration isolation system of the inertial reference corner cube in a laser interference absolute gravimeter. Results of numerical calculations conducted under vibration interference conditions with added white noise resulting in a signal-to-noise ratio of 40 dB demonstrate the following. The accuracy and standard deviation of the gravimeter obtained using the proposed algorithm are −0.04 µGal (1µGal=1×10-8 m s−2) and 0.24 µGal, respectively, while those values obtained by the standard least-squares solution are 10.19 and 154.11 µGal, respectively. The test results indicate that the average response of the reference value of acceleration due to gravity superimposed by a disturbance of 1.00 µGal is 1.01 µGal using the proposed algorithm and 0.87 µGal using the standard least-squares solution.

Design Methodology of a Passive Vibration Isolation System for an Optical System With Sensitive Line-of-Sight

The performance of an optical system with sensitive line-of-sight (LOS) is influenced by rotational vibration. In view of this, a design methodology is proposed for a passive vibration isolation system in an optical system with sensitive LOS. Rotational vibration is attributed to two sources: transmitted from the mounting base and generated by modal coupling. Therefore, the elimination of the rotational vibration caused by coupling becomes an important part of the design of the isolation system. Additionally, the decoupling conditions of the system can be obtained. When the system is totally decoupled, the vibration on each degree of freedom (DOF) can be analyzed independently. Therefore, the stiffness and damping coefficient on each DOF could be obtained by limiting the vibration transmissibility, in accordance to actual requirements. The design of a vibration isolation system must be restricted by the size and shape of the payload and the installation space, and the layout constrains are thus also discussed.

Performance Enhancement of Spaceborne Cooler Passive Launch and On-Orbit Vibration Isolation System

A spaceborne cryogenic cooler induces undesirable microvibration disturbances during its on-orbit operation, which is one of the main sources that degrades the image quality of submeter-level high-resolution observation satellites. Several types of vibration isolation systems based on passive approaches have been developed for reducing the microvibration of the cooler. A coil-spring-type passive vibration isolation system developed in a previous study has shown excellent performance in both launch vibration and on-orbit microvibration isolation. To improve the capability of the conventional cooler isolator, including the position sensitivity and launch vibration reduction, we propose a new version of a dual coil-spring-type passive vibration isolator system. The effectiveness of the newly proposed design was validated through a microjitter measurement test, position sensitivity test, and qualification-level launch vibration test of the isolator.

Modeling and control of magnetorheological 6-DOF stewart platform based on multibody systems transfer matrix method

A 6-DOF vibration isolation system with magneto-rheological damper (MRD) based on Stewart mechanism was designed to reduce the mechanical vibration more effectively. To make the isolation system perform well, an effective control method was also proposed. Using the linear multibody systems transfer matrix method (MSTMM), the dynamic model of the MRD 6-DOF vibration isolation system was established to obtain the dynamic characteristics. Firstly, based on the test mechanical property of magnetorheological damper, the electromagnetic coupling model of magnetorheological damper was established. Secondly, the transfer equation of 6-DOF vibration isolation system was established by linear MSTMM. And the state space equation was derived using the modal superposition method, which was based on the augmented eigenvector and body dynamics equation. Thirdly, the linear quadratic Gaussian control method of MRD 6-DOF vibration isolation system was designed. Finally, the numerical simulation was carried out. The results showed that MRD 6-DOF vibration isolation system with optimal control improved the dynamic performance of mechanical equipment effectively. Compared with passive vibration isolation system, the translation of the vibration isolation system in the X, Y, and Z directions, as well as the rotation around the X axis, Y axis and Z axis were reduced by 51.85%, 58.71%, 64.43%, 75.43%, 66.45% and 52.87%, respectively. Similarly, the percentage drops were 50.00%, 56.16%, 34.94%, 53.09%, 38.14% and 46.76% compared to the PID control based vibration isolation system, respectively. The established dynamic model and control strategy provided theoretical basis for relevant vibration isolation tests.

An active actuator based on giant magnetostrictive composite pendulum for vibration isolation

This paper proposes an active actuator based on giant magnetostrictive composite pendulum for vibration isolation, laying the foundation for vertical micro-vibration isolation. The performance of a single-stage pendulum vibration isolation system can be improved by increasing the pendulum length, along with the influence of the environment on the system increases. In precise experiments, effective isolation of vertical micro-vibration improves the accuracy of the experiments. Interference caused by micro-vibration can be attenuated by designed magnetostrictive actuators. Then, a suspension actuator consists of a composite pendulum and a driving device is designed. The composite pendulum is composed of a quartz fiber coated with a giant magnetostrictive material (GMM). The GMM can achieve the desired small strain in a designed magnetic field. GMM is applied on a quartz fiber to form a composite pendulum. Therefore, low-frequency active vibration isolation of single pendulum is realized. Compared with the passive vertical vibration isolation system, the system gets better vibration isolation and anti-interference ability. Compared with the traditional active vertical vibration isolation system, it has the advantages of system simplification, high integration and high sensitivity.

Dynamic research on a low-frequency vibration isolation system of quasi-zero stiffness

The paper describes an establishment of dynamic characteristics of the newly created passive mechanical system for isolation of low-frequency (0.7 Hz–50 Hz) vibrations. The many metrological means are sensitive to mechanical vibrations and acoustic noise of low frequency. Such may appear both outside and inside a building, i.e. may be caused by wind, heating, aeration, air conditioning equipment, moving vehicles and other. In the paper, description of the theoretical and experimental tests is provided. The obtained dynamic characteristics (transmissibilities) of the passive mechanical low-frequency vibration isolation system show that such a system is able to isolate vibrations effectively in the frequency range of 0.7 Hz–50 Hz. The results of the experimental tests support the results of the theoretical research.

Bio-inspired anti-vibration with nonlinear inertia coupling

Abstract This paper presents a unique human body inspired passive vibration isolation system with a special coupled nonlinear inertia design. This human body inspired anti-vibration structure with nonlinear inertia consists of a compact X-shaped structure with a horizontally-installed spring system to simulate the functions of legs and muscles, and a compact rotational unit to mimic the arms swinging (or upper body movement) and/or muscle extension-flexion motion during human walking. It is particularly focused on the beneficial nonlinear effect incurred by the rotational unit, including a nonlinear equivalent mass and a very special nonlinear inertia incurred conservative force. It is shown that, the nonlinear properties (in equivalent stiffness, damping and mass simultaneously) can obviously improve the vibration isolation at low frequencies and/or in a broadband frequency range, and increase the stability of the mass center of the overall isolation system during vibration, irrespective of the loading and excitation conditions. The muscle function and swinging arms of human body are for the first time employed with an innovative and simple mechanical design for vibration control and successfully validated by experimental prototypes for their excellent beneficial nonlinear features. This paper presents a unique simple passive and adjustable anti-vibration solution of great potential in extensive engineering applications.