scholarly journals Non-Linear Vibration Isolators with Unknown Excitation and Unmodelled Dynamics: Sliding Mode Active Control

2019 ◽  
Vol 9 (17) ◽  
pp. 3567 ◽  
Author(s):  
Zhang ◽  
Hu ◽  
Liu ◽  
Ouyang ◽  
Zhang
Keyword(s):  
Sliding Mode ◽  
Control Methods ◽  
Practical Application ◽  
Linear Vibration ◽  
Single Degree Of Freedom ◽  
Vibration Isolators ◽  
Single Degree ◽  
Non Linear ◽  
The One ◽  
Twisting Algorithm

For a class of single-degree-of-freedom non-linear passive vibration isolators with unknown excitation and unmodelled dynamics, two sliding mode control methods—a conventional one and the other using a super-twisting algorithm—were proposed to complement and improve the performances and the robustness of the passive isolators. The proposed control methods only require the estimation of the loading and measured velocities of the isolators. Numerical simulations for a non-linear isolator with quasi-zero stiffness demonstrated that both methods were effective and easy to implement, and the one using a super-twisting algorithm was more promising from the perspective of practical application.

scholarly journals The Transmissibility of Vibration Isolators With a Nonlinear Antisymmetric Damping Characteristic

2010 ◽  
Vol 132 (1) ◽  
Author(s):  
Z. K. Peng ◽  
Z. Q. Lang ◽  
X. J. Jing ◽  
S. A. Billings ◽  
G. R. Tomlinson ◽  
...  
Keyword(s):  
Resonance Frequency ◽  
Frequency Region ◽  
Simulation Studies ◽  
Vibration Isolator ◽  
Linear Vibration ◽  
Output Frequency ◽  
Single Degree Of Freedom ◽  
Vibration Isolators ◽  
Single Degree ◽  
Force Transmissibility

In the present study, the concept of the output frequency response function, recently proposed by the authors, is applied to theoretically investigate the force transmissibility of single degree of freedom (SDOF) passive vibration isolators with a nonlinear antisymmetric damping characteristic. The results reveal that a nonlinear antisymmetric damping characteristic has almost no effect on the transmissibility of SDOF vibration isolators over the ranges of frequencies, which are much lower or higher than the isolator’s resonance frequency. On the other hand, the introduction of a nonlinear antisymmetric damping can significantly reduce the transmissibility of the vibration isolator over the resonance frequency region. The results indicate that nonlinear vibration isolators with an antisymmetric damping characteristic have great potential to overcome the dilemma encountered in the design of passive linear vibration isolators, that is, increasing the level of damping to reduce the transmissibility at the resonance could increase the transmissibility over the range of higher frequencies. These important theoretical conclusions are then verified by simulation studies.

A Method for Type Synthesis of Mechanisms Using Phase Diagrams

1994 ◽  
Author(s):  
Sio-Hou Lei ◽  
Ying-Chien Tsai
Keyword(s):  
Phase Diagram ◽  
Degrees Of Freedom ◽  
Practical Application ◽  
Type Synthesis ◽  
Planar Mechanisms ◽  
Simple Loop ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Spatial Mechanisms ◽  
Synthesis Of Mechanisms

Abstract A method for synthesizing the types of spatial as well as planar mechanisms is expressed in this paper by using the concept of phase diagram in metallurgy. The concept represented as a type synthesis technique is applied to (a) planar mechanisms with n degrees of freedom and simple loop, (b) spatial mechanisms with single degree of freedom and simple loop, to enumerate all the possible mechanisms with physically realizable kinematic pairs. Based on the technique described, a set of new reciprocating mechanisms is generated as a practical application.

Kinematic Drift of Single-Axis Gyroscopes

1958 ◽  
Vol 25 (3) ◽  
pp. 357-360
Author(s):  
R. H. Cannon
Keyword(s):  
Experimental Verification ◽  
Spatial Orientation ◽  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Momentum Vector ◽  
Single Degree ◽  
The One ◽  
Platform Motions

Abstract A gyroscope can incur steady drift by kinematically rectifying angular vibrations of the platform on which it is mounted. The phenomenon, for an unrestrained single-degree-of-freedom gyro, results from oscillatory precession of the gyro momentum vector from its nominal spatial orientation, so that it senses platform motions about axes other than the one it is controlling. The magnitude of the drift can be accurately predicted and the vibration climate of the platform restricted accordingly. Quantitative experimental verification is presented.

Effectiveness of neoprene pad vibration isolators at high frequencies

2021 ◽  
Vol 263 (4) ◽  
pp. 2172-2183
Author(s):  
Jerry Lilly
Keyword(s):  
Natural Frequency ◽  
Insertion Loss ◽  
Dynamic Stiffness ◽  
Degree Of Freedom ◽  
Frequency Wave ◽  
Single Degree Of Freedom ◽  
High Frequencies ◽  
Vibration Isolators ◽  
Single Degree ◽  
Wide Range

The natural frequency, dynamic stiffness, and insertion loss of commercially available neoprene pad vibration isolators have been measured in a simple, single degree of freedom system over a wide range of pad loadings out to a maximum frequency of 10 kHz. The results reveal that dynamic stiffness can vary significantly with pad loading as well as the durometer of the material. It will also be shown that insertion loss follows the theoretical single degree of freedom curve only out to a frequency that is about 5 to 10 times the natural frequency, depending upon the pad durometer rating. Above that frequency wave resonances in the material cause the insertion loss to deteriorate significantly out to a frequency near 1 kHz, above which the insertion loss maintains a relatively constant value, again depending upon the pad durometer rating. In some instances the insertion loss values can approach 0 dB or even become negative at specific frequencies in the frequency region that is 10 to 20 times the natural frequency of the system.

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