Vibration Isolation of Precision Payloads for Aerial Vehicles Using Magnetorheological Isolators

2005 ◽  
Author(s):  
Young-Tai Choi ◽  
Mikel Brigley ◽  
Norman M. Wereley
Keyword(s):  
Vibration Isolation ◽  
Control Input ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Aerial Vehicles ◽  
Lqg Control ◽  
Field Control ◽  
Aerial Vehicle ◽  
Vibration Isolation Performance ◽  
Isolation Performance

This study addresses the application of MR (magnetorheological) isolators to vibration isolation of precision payloads for aerial vehicles. To this end, a precision payload in an aerial vehicle is modeled as a six-degree-of-freedom (DOF) lumped parameter model of a sensor assembly. An MR isolator is modeled as a 3-DOF passive spring-damping element and a 3-DOF semi-active yield force due to the yield stress of an MR fluid. Three MR isolators are configured with equal installation angles between the precision payload and the base structure in the aerial vehicle. The governing equations of motion for the MR vibration isolation system of the precision payload for the aerial vehicle are derived and then key parameters of the MR isolators, such as stiffness, damping, and isolator orientation, are determined via a global optimization method. The simulated response of the passive MR vibration isolation system with no magnetic field control input and constant magnetic field control input are presented and analyzed under different excitation conditions. To improve the passive MR vibration isolation performance, a linear quadratic Gaussian (LQG) control algorithm is designed. Finally, simulated responses of the semi-active MR vibration isolation performance using LQG control are evaluated and compared with those of passive (zero or constant field) MR vibration isolation systems.

scholarly journals Experimental Validation of Fly-Wheel Passive Launch and On-Orbit Vibration Isolation System by Using a Superelastic SMA Mesh Washer Isolator

2017 ◽  
Vol 2017 ◽  
pp. 1-16 ◽  
Author(s):  
Seong-Cheol Kwon ◽  
Mun-Shin Jo ◽  
Hyun-Ung Oh
Keyword(s):  
Vibration Isolation ◽  
Application Form ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Static Tests ◽  
Resolution Observation ◽  
Passive Vibration Isolation ◽  
Basic Characteristics ◽  
Vibration Isolation Performance ◽  
Isolation Performance

On-board appendages with mechanical moving parts for satellites produce undesirable micro-jitters during their on-orbit operation. These micro-jitters may seriously affect the image quality from high-resolution observation satellites. A new application form of a passive vibration isolation system was proposed and investigated using a pseudoelastic SMA mesh washer. This system guarantees vibration isolation performance in a launch environment while effectively isolating the micro-disturbances from the on-orbit operation of jitter source. The main feature of the isolator proposed in this study is the use of a ring-type mesh washer as the main axis to support the micro-jitter source. This feature contrasts with conventional applications of the mesh washers where vibration damping is effective only in the thickness direction of the mesh washer. In this study, the basic characteristics of the SMA mesh washer isolator in each axis were measured in static tests. The effectiveness of the design for the new application form of the SMA mesh washer proposed in this study was demonstrated through both launch environment vibration test at qualification level and micro-jitter measurement test which corresponds to on-orbit condition.

Vibration Isolation and Chaotic Vibration

2003 ◽  
Author(s):  
Rong-Jun Jiang ◽  
Shi-Jian Zhu
Keyword(s):  
Nonlinear Vibration ◽  
Vibration Isolation ◽  
Harmonic Excitation ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Chaotic Vibration ◽  
Vibration State ◽  
Vibration Isolation Performance ◽  
Isolation Performance ◽  
Better Than

Taking single degree of freedom vibration isolation system under simple harmonic excitation as an example, and considering the energy, the vibration isolation performance in different conditions was studied theoretically and numerically. The results shows that when the simple harmonic excitation import energy is definite, the vibration isolation performance at the primary harmonic frequency of the nonlinear vibration isolation system is better than that of the linear system, and the vibration isolation performance of the nonlinear vibration isolation system in chaotic vibration state is much better than that in non-chaotic vibration state. For the same isolated object, if can let the vibration isolation system vibrate chaotically, the system will possess the best isolation performance at the primary frequency.

scholarly journals Shock response of a two-stage vibration isolation system

2020 ◽  
Vol 21 (2) ◽  
pp. 1-11
Author(s):  
Diego Francisco Ledezma Ramirez ◽  
Pablo Ernesto Tapia Gonzalez ◽  
Martín Castillo Morales ◽  
Tania Paloma Berber Solano ◽  
Adriana Salas Zamarripa
Keyword(s):  
Vibration Isolation ◽  
Two Stage ◽  
Isolation System ◽  
Short Pulses ◽  
Vibration Isolation System ◽  
Secondary Stage ◽  
Shock Response ◽  
Vibration Isolation Performance ◽  
Two Degree Of Freedom ◽  
Isolation Performance

Abstract. Two-degree of freedom system, or two-stage mount are used to improve the high frequency vibration isolation performance with the disadvantage of increasing the mass of the system and adding a second resonance. The vibration isolation property is a well-understood topic for harmonic vibration considering linear and nonlinear elements, but not its shock response. The absolute and relative response of a two-stage mount under shock excitation is investigated in this paper. Analysing the effect of the mass ratio between the two-stage, and its respective viscous damping. The potential advantages and issues behind this system are discussed and compared with the single mount. Experimental validation was performed using two commercial isolator and different masses. Findings suggested that a large secondary mass could reduce the shock response in terms of absolute motion. This effect is only significant for the case of short pulses and when the added mass is at least five times greater than the main mass. Being useful to have light damping only on the secondary stage.

scholarly journals A Vibration Isolation System Using the Negative Stiffness Corrector Formed by Cam-Roller Mechanisms with Quadratic Polynomial Trajectory

2020 ◽  
Vol 10 (10) ◽  
pp. 3573 ◽  
Author(s):  
Mengnan Sun ◽  
Zhixu Dong ◽  
Guiqiu Song ◽  
Xingwei Sun ◽  
Weijun Liu
Keyword(s):  
Vibration Isolation ◽  
Quadratic Polynomial ◽  
Negative Stiffness ◽  
Calculation Error ◽  
Vibration Isolator ◽  
Isolation System ◽  
Frequency Wave ◽  
Vibration Isolation System ◽  
Vibration Isolation Performance ◽  
Isolation Performance

The vibration isolator equipped with a negative stiffness corrector (NSC) excels at vibration isolation, but its stiffness often presents complex nonlinearity which needs to be approximated in calculation. To avoid the harmful effects of approximate stiffness, the NSC formed by the cam-roller mechanism with a quadratic polynomial trajectory (QCRM) is proposed to construct the vibration isolation system. From the inherent geometrical relationship in the structure, the generation mechanism of high-static-low-dynamic stiffness is analyzed, and the quasi-zero stiffness (QZS) condition of the system is derived. Based on the dynamic model of the QZS vibration isolator, the functions of response characteristics are solved by the harmonic balance method. Then, the absolute displacement transmissibility with different parameter values, and the vibration isolation performance under sinusoidal, multi-frequency wave, and random excitations are discussed. The simulated results show that the stiffness expression of the proposed QZS vibration isolator is directly a quadratic function, which removes the calculation error caused by approximate stiffness at large displacement and broadens the available isolation displacement range. Introducing the QCRM-NSC can significantly suppress the low-frequency vibration and resonance response without changing the load-bearing capacity of the vibration isolator. Under various excitations, the vibration isolation performance of the QZS vibration isolator all outperforms the linear counterpart.

Design and analysis of a vibration isolation system with cam–roller–spring–rod mechanism

2021 ◽  
pp. 107754632110005
Author(s):  
Yonglei Zhang ◽  
Guo Wei ◽  
Hao Wen ◽  
Dongping Jin ◽  
Haiyan Hu
Keyword(s):  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Experimental Studies ◽  
Excitation Amplitude ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Stiffness Characteristic ◽  
Negative Stiffness Mechanism ◽  
Isolation Systems ◽  
Vibration Isolation Performance

The vibration isolation system using a pair of oblique springs or a spring-rod mechanism as a negative stiffness mechanism exhibits a high-static low-dynamic stiffness characteristic and a nonlinear jump phenomenon when the system damping is light and the excitation amplitude is large. It is possible to remove the jump via adjusting the end trajectories of the above springs or rods. To realize this idea, the article presents a vibration isolation system with a cam–roller–spring–rod mechanism and gives the detailed numerical and experimental studies on the effects of the above mechanism on the vibration isolation performance. The comparative studies demonstrate that the vibration isolation system proposed works well and outperforms some other vibration isolation systems.

scholarly journals Active stabilization of unmanned aerial vehicle imaging platform

2020 ◽  
Vol 26 (19-20) ◽  
pp. 1791-1803 ◽  
Author(s):  
Mohit Verma ◽  
Vicente Lafarga ◽  
Mael Baron ◽  
Christophe Collette
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Unmanned Aerial Vehicle ◽  
Vibration Isolation ◽  
Isolation System ◽  
Aerial Vehicles ◽  
Active Stabilization ◽  
Aerial Vehicle ◽  
Active Vibration ◽  
Improved Performance

The advancement in technology has seen a rapid increase in the use of unmanned aerial vehicles for various applications. These unmanned aerial vehicles are often equipped with the imaging platform like a camera. During the unmanned aerial vehicle flight, the camera is subjected to vibrations which hamper the quality of the captured images/videos. The high-frequency vibrations from the unmanned aerial vehicle are transmitted to the camera. Conventionally, passive rubber mounts are used to isolate the camera from the drone vibrations. The passive mounts are able to provide reduction in response near the resonance. However, this comes at the cost of amplification of response at the higher frequency. This article proposes an active vibration isolation system which exhibits improved performance at the higher frequencies than the conventional system. The active isolation system consists of a contact-less voice coil actuator supported by four springs. Experiments are carried out to study the effect of vibrations on the quality of images captured. The characterization of drone vibrations is also carried out by recording the acceleration during different flight modes. The performance of the proposed isolation system is experimentally validated on a real drone camera subjected to the recorded drone acceleration spectrum. The isolation system is found to perform better than the conventional rubber mounts and is able to reduce the vibrations to a factor of one-fourth. It can be effectively used to improve the image acquisition quality of the unmanned aerial vehicles.

The Research on Robust LQ Control Applied to Uncertain Vibration Isolation System

2010 ◽  
Vol 34-35 ◽  
pp. 1289-1293
Author(s):  
Qiang Hong Zeng ◽  
Qi Wei He ◽  
Jing Jun Lou
Keyword(s):  
Optimal Control ◽  
Transfer Function ◽  
Vibration Isolation ◽  
Multi Objective Optimization ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Robust Optimal Control ◽  
Result Show ◽  
Isolation Performance ◽  
Lq Control

Synthesized considering several performance target, robust optimal control was applied to uncertain double layer vibration isolation system then the transfer function was got between input disturbance and out performance. By analyzing the amplitude-frequency characteristics of transfer function, the result show that the robust LQ control can successfully improve the isolation performance of uncertain hybrid vibration isolation system, realize the multi-objective optimization.

scholarly journals High-Efficiency Vibration Isolation for a Three-Phase Power Transformer by a Quasi-Zero-Stiffness Isolator

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Hao Cao ◽  
Yaopeng Chang ◽  
Jiaxi Zhou ◽  
Xuhui Zhao ◽  
Ling Lu ◽  
...  
Keyword(s):  
Vibration Isolation ◽  
High Efficiency ◽  
Power Transformer ◽  
Dynamic Stiffness ◽  
Harmonic Balance Method ◽  
Isolation System ◽  
Three Phase ◽  
Engineering Practices ◽  
Vibration Isolation Performance ◽  
Isolation Performance

The vibrations generated by a three-phase power transformer reduce the comfort of residents and the service life of surrounding equipment. To resolve this tough issue, a quasi-zero-stiffness (QZS) isolator for the transformer is proposed. This paper is devoted to developing a QZS isolator in a simple way for engineering practices. The vertical springs are used to support the heavy weight of the transformer, while the oblique springs are employed to fulfill negative stiffness to neutralize the positive stiffness of the vertical spring. Hence, a combination of the vertical and oblique spring can yield high static but low dynamic stiffness, and the vibration isolation efficiency can be improved substantially. The dynamic analysis for the QZS vibration isolation system is conducted by the harmonic balance method, and the vibration isolation performance is estimated. Finally, the prototype of the QZS isolator is manufactured, and then the vibration isolation performance is tested comparing with the linear isolator under real power loading conditions. The experimental results show that the QZS isolator prominently outperforms the existing linear isolator. This is the first time to devise a QZS isolator for three-phase power transformers with heavy payloads in engineering practices.

scholarly journals Modeling and Control of a Six Degrees of Freedom Maglev Vibration Isolation System

Sensors ◽  
2019 ◽  
Vol 19 (16) ◽  
pp. 3608 ◽  
Author(s):  
Qianqian Wu ◽  
Ning Cui ◽  
Sifang Zhao ◽  
Hongbo Zhang ◽  
Bilong Liu
Keyword(s):  
Dynamic Model ◽  
Nonlinear Dynamic ◽  
Degrees Of Freedom ◽  
Vibration Isolation ◽  
Nonlinear Dynamic Model ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Modeling And Control ◽  
And Control ◽  
Isolation Performance

The environment in space provides favorable conditions for space missions. However, low frequency vibration poses a great challenge to high sensitivity equipment, resulting in performance degradation of sensitive systems. Due to the ever-increasing requirements to protect sensitive payloads, there is a pressing need for micro-vibration suppression. This paper deals with the modeling and control of a maglev vibration isolation system. A high-precision nonlinear dynamic model with six degrees of freedom was derived, which contains the mathematical model of Lorentz actuators and umbilical cables. Regarding the system performance, a double closed-loop control strategy was proposed, and a sliding mode control algorithm was adopted to improve the vibration isolation performance. A simulation program of the system was developed in a MATLAB environment. A vibration isolation performance in the frequency range of 0.01–100 Hz and a tracking performance below 0.01 Hz were obtained. In order to verify the nonlinear dynamic model and the isolation performance, a principle prototype of the maglev isolation system equipped with accelerometers and position sensors was developed for the experiments. By comparing the simulation results and the experiment results, the nonlinear dynamic model of the maglev vibration isolation system was verified and the control strategy of the system was proved to be highly effective.

On an Improvement of Hybrid Vibration Isolation System

1997 ◽  
Author(s):  
Kazuki Mizutani ◽  
Yoshitaka Fujita ◽  
Ryojun Ikeura
Keyword(s):  
Hybrid System ◽  
Vibration Isolation ◽  
Control Method ◽  
Weighting Function ◽  
Phase Lag ◽  
Frequency Range ◽  
Active System ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Isolation Performance

Abstract This paper proposes a hybrid-type vibration isolation system controlled by a phase compensated LQ control method with a frequency shaped weighting function. The hybrid system is composed of a passive spring-damper system reducing vibrations of high frequency range and an active one reducing those of low frequency range. This system is controlled by the phase compensated digital LQ optimization method with a frequency shaped weighting function. By the proposed method, the phase-lag of the control system is compensated so that the vibration isolation performance is improved. Simulations for the active system are carried out and the effectiveness of the phase compensation is shown. Then, experiments for the hybrid system are carried out for sinusoidal or random excitations. It is confirmed that the purposed hybrid system has the excellent isolation performance for excited vibrations over the wide frequency range.

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