Closed-loop performance of a vibration isolation and suppression system

1997 ◽  
Author(s):  
J. Sullivan ◽  
Z. Rahman ◽  
R. Cobb ◽  
J. Spanos
Keyword(s):  
Vibration Isolation ◽  
Closed Loop ◽  
Suppression System

Vibration isolation and suppression system for precision payloads in space

1999 ◽  
Vol 8 (6) ◽  
pp. 798-812 ◽  
Author(s):  
Richard G Cobb ◽  
Jeanne M Sullivan ◽  
Alok Das ◽  
L Porter Davis ◽  
T Tupper Hyde ◽  
...  
Keyword(s):  
Vibration Isolation ◽  
Suppression System

scholarly journals Type Synthesis of 3-Translational Redundant Actuated Parallel Mechanisms With Closed-Loop Branch Chains Based On Graphical Approach

2021 ◽  
Author(s):  
Yongquan Li ◽  
Hong-Sheng Jiang ◽  
Tian-Yu Zheng ◽  
Ke-Long Xi ◽  
Han Jing ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Parallel Mechanism ◽  
Large Scale ◽  
Vibration Isolation ◽  
Closed Loop ◽  
Screw Theory ◽  
Simple Calculation ◽  
Parallel Mechanisms ◽  
Logistics Industry ◽  
Graphical Approach

Abstract The 3-translational parallel mechanism is widely used in industrial, medical, and military fields, among others. With the development of the national logistics industry, a pressing need for a kind of 3-translational parallel mechanism emerged. Such mechanisms have high stiffness and high bearing capacity and are used for cargo handling and sorting. A novel method based on the graphical approach was proposed for the synthesis of 3-translational redundancy actuated parallel mechanism with closed-loop branch chains. The new mechanism has four symmetrically arranged branch chains, which eases subsequent kinematics and dynamics analyses while providing good mechanical properties. Based on the graphical approach theory, according to the constraint number contained in the branch chain, two types of redundant driven branch chains with closed-loop structures were constructed. The first type includes rotation constraint in one direction, while the second type includes the rotation constraint in two directions. Based on various combinations of two branch chain types, their allocation schemes can be divided into two types. Moreover, said these two allocation schemes can be integrated into at least 500 and 400 types of 3-translational redundant actuated parallel mechanisms with closed-loop branch chains. Then, the degree of freedom properties of representative mechanisms were tested using the screw theory. A large number of novel mechanisms were integrated assessed using this method, and branch chains such mechanisms were symmetrically distributed. They have a strong bearing capacity, simple calculation, and control, and can be applied to the handling and sorting of goods, large-scale precision machine tools, and large construction machinery vibration isolation systems, among others.

Simulation of Multi-Closed Loop Control With Feed Forward Control of Micro-Vibration Isolation Platform

2014 ◽  
Author(s):  
Qianqian Wu ◽  
Honghao Yue ◽  
Rongqiang Liu ◽  
Liang Ding ◽  
Zongquan Deng
Keyword(s):  
Vibration Isolation ◽  
Closed Loop ◽  
Control Method ◽  
Magnetic Levitation ◽  
Low Frequency ◽  
Closed Loop Control ◽  
Vibration Source ◽  
Feed Forward ◽  
Loop Control ◽  
Micro Vibration

Micro vibration in the ideal-zero gravity environments has complicated science experiment results. A magnetic levitation vibration isolation platform is needed to isolate the vibration source to provide acceptable acceleration level in low frequency range. The configuration of the Lorentz actuators is discussed in the paper. And the modeling of the transformation matrix from the force to the current is deduced. In order to generate desired force, the current is needed to predict precisely. To study the characteristics of the system, the single degree of freedom system is analyzed. A multi-closed loop control scheme is put forward to achieve vibration isolation control. To evaluate the effect of each control parameter, frequency domain analysis of the transfer function is simulated. In order to further increase the control effectiveness, a feed forward compensation control algorithm is added to control the vibration of cables that connect the upper platform and the base. By regulating these control parameters, bode curves can be obtained. Comparing the two methods, it can be concluded that the control method with feed forward compensation is better than the one without that.

scholarly journals Stability and convergence analysis for different harmonic control algorithm implementations

2015 ◽  
Vol 23 (8) ◽  
pp. 1231-1247 ◽  
Author(s):  
Ilias Zazas ◽  
Steve Daley
Keyword(s):  
Stability Analysis ◽  
Vibration Isolation ◽  
Closed Loop ◽  
Linear Time ◽  
Excitation Frequency ◽  
Stability And Convergence ◽  
Speed Of Convergence ◽  
Harmonic Control ◽  
Disturbance Frequency ◽  
Loop Stability

In many engineering systems there is a common requirement to isolate the supporting foundation from low frequency periodic machinery vibration sources. In such cases the vibration is mainly transmitted at the fundamental excitation frequency and its multiple harmonics. It is well known that passive approaches have poor performance at low frequencies and for this reason a number of active control technologies have been developed. For discrete frequencies disturbance rejection Harmonic Control (HC) techniques provide excellent performance. In the general case of variable speed engines or motors, the disturbance frequency changes with time, following the rotational speed of the engine or motor. For such applications, an important requirement for the control system is to converge to the optimal solution as rapidly as possible for all variations without altering the system's stability. For a variety of applications this may be difficult to achieve, especially when the disturbance frequency is close to a resonance peak and a small value of convergence gain is usually preferred to ensure closed-loop stability. This can lead to poor vibration isolation performance and long convergence times. In this paper, the performance of two recently developed HC algorithms are compared (in terms of both closed-loop stability and speed of convergence) in a vibration control application and for the case when the disturbance frequency is close to a resonant frequency. In earlier work it has been shown that both frequency domain HC algorithms can be represented by Linear Time Invariant (LTI) feedback compensators each designed to operate at the disturbance frequency. As a result, the convergence and stability analysis can be performed using the LTI representations with any suitable method from the LTI framework. For the example mentioned above, the speed of convergence provided by each algorithm is compared by determining the locations of the dominant closed-loop poles and stability analysis is performed using the open-loop frequency responses and the Nyquist criterion. The theoretical findings are validated through simulations and experimental analysis.

Vibration Isolation Control Via Simultaneous Left and Right Eigenvector Assignment

2005 ◽  
Author(s):  
T. Y. Wu ◽  
K. W. Wang
Keyword(s):  
Disturbance Rejection ◽  
Vibration Isolation ◽  
Closed Loop ◽  
Integrated System ◽  
Loop System ◽  
Closed Loop System ◽  
Left Eigenvector ◽  
Assignment Method ◽  
Left And Right ◽  
New Formulation

The objective of this research is to investigate the feasibility of utilizing the simultaneous left and right eigenvector assignment concept for vibration isolation feedback control design. The purpose of the right eigenvector assignment method is to alter the closed-loop system modes such that the modal components corresponding to the concerned regions (isolation end of an isolator) have relatively small amplitude. Correspondently, the design goal of left eigenvector assignment is to alter the left eigenvectors of the closed-loop system so that they are as closely orthogonal to the system’s forcing vectors as possible. With this approach, one can achieve both disturbance rejection and modal confinement concurrently for the purpose of vibration isolation. In this research, a new formulation is developed so that the desired left eigenvectors of this integrated system are selected through solving a generalized eigenvalue problem, where the orthogonality indices between the forcing vector and the left eigenvectors are minimized. The components of right eigenvectors corresponding to the concerned regions are minimized concurrently. To realistically implement the algorithm, an integrated closed-loop system with state estimator is developed. Numerical simulations are performed to evaluate the effectiveness of the proposed method on concurrent disturbance rejection and modal confinement for a isolator rod design. Frequency responses of the isolator in the selected frequency range are illustrated. It is shown that with the simultaneous left-right eigenvector assignment technique, both disturbance rejection and modal confinement can be achieved, and thus the vibration amplitude in the isolated regions can be suppressed significantly.

Robust QFT Control of a Piezo-Based Vibration Isolation System With Consideration of Hysteresis Effect

Volume 1 ◽  
2004 ◽  
Author(s):  
Meng-Shiun Tsai ◽  
Feng-Ching Chiang ◽  
Yan-Shuo Sun ◽  
Jen-Hua Wu
Keyword(s):  
Disturbance Rejection ◽  
Vibration Isolation ◽  
Closed Loop ◽  
Approximate Model ◽  
Hysteresis Effect ◽  
Hysteresis Model ◽  
Robust Performance ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Three Degree Of Freedom

In this paper, we investigate a three-degree-of-freedom (X-Y-Z) piezo-based vibration isolation platform. The hysteresis effect together with system uncertainties are represented by an approximate model. The approximate model consists of a variable gain and variable time-delay which are the functions of the input magnitude and frequency. Experiments are performed to identify the parameters of the proposed approximate model. To achieve robust performance of the isolation system with consideration of the hysteresis effect, quantitative feedback theory (QFT) controller is proposed. The hysteresis model is naturally built into the template of plant. It is shown from closed loop experiments that the designed controller can achieve high disturbance rejection within the bandwidth of 10–60Hz for the MIMO vibration isolation system.

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