The evaluation of two methods for active vibration damping using RUS Hexapod platform

2018 ◽  
Vol 41 (5) ◽  
pp. 1207-1215 ◽  
Author(s):  
Nael Nashawati ◽  
Chadi Albitar ◽  
Alaa Dib
Keyword(s):  
Vibration Isolation ◽  
Control Method ◽  
Least Mean Square ◽  
Spherical Joint ◽  
Low Frequencies ◽  
Feed Forward Control ◽  
Joint Structure ◽  
Active Vibration Damping ◽  
Fuzzy Logic Method ◽  
Active Vibration

This paper presents a study on active vibration Isolation using RUS (revolute joint, universal joint, spherical joint) structure of Stewart platform, as it is less expensive and easier to build than PSS (prismatic joint, spherical joint, spherical joint) structure, which is used a lot in this field. Two control methods are proposed; the fuzzy logic method and the adaptive feed forward control method with multiple error least mean square. Results are evaluated using the SimMechanics toolbox under Matlab 2014 with white noise signals to simulate vibrations. In addition, practical measured accelerations are applied and results are evaluated. Both strategies use a proportional–integral–derivative (PID) controller in parallel to control displacements of the Hexapod as vibrations at low frequencies generate high variations in displacements. The results prove that using a Hexapod with RUS structure can degrade vibrations and guarantee a good behavior for many applications, which is the main aim of this research.

Recent Study on the Passive and Active Vibration Isolators

2014 ◽  
Vol 494-495 ◽  
pp. 491-496
Author(s):  
Hua Ping Mei ◽  
Hao Yue Tian ◽  
Shuan Huang
Keyword(s):  
Vibration Isolation ◽  
Control Method ◽  
Low Frequency ◽  
Research Direction ◽  
Magnetic Suspension ◽  
High Frequency Oscillation ◽  
Future Research ◽  
Vibration Isolator ◽  
Vibration Isolators ◽  
Active Vibration

The vibration isolators have witnessed significant developments due to pressing demands for high resolution metrology and manufacturing, optical, physical and chemical experiments. In the view of these requirements, the engineers and physicists have exploited different types of vibration isolators. This paper firstly presents the recent developments on the passive vibration isolators. It finds that the passive vibration isolators can constrain the high frequency oscillation. The active control is the efficient method to cancel the low frequency vibration. Then, the paper is concerned with the recent advances on the active vibration isolator. The appropriate actuator, sensor and advanced control method are the key component of the active vibration isolator to enhance their vibration isolation properties. Finally, the author proposes that the magnetic suspension vibration isolator is a future research direction in the field of the vibration isolation.

A Study of Active Vibration Isolation

1985 ◽  
Vol 107 (4) ◽  
pp. 392-397 ◽  
Author(s):  
N. Tanaka ◽  
Y. Kikushima
Keyword(s):  
Vibration Isolation ◽  
Control Method ◽  
Feedforward Control ◽  
Ground Vibration ◽  
Design Parameters ◽  
Isolation Method ◽  
Isolation System ◽  
Active Isolation ◽  
Active Vibration ◽  
Active Vibration Isolation

For the purpose of suppressing ground vibration produced by vibrating machines, such as forging hammers, press machines, etc., this paper presents an active vibration isolation method. Unlike conventional isolators, the active isolator proposed in this paper permits rigid support of the machines. First, the principle of the active isolation method is shown, and the system equations are derived. Secondly, the characteristics and the design parameters of the active isolation system are presented. Thirdly, from the point of view of the feedforward control method, the dynamic compensators are designed so as to sufficiently suppress the exciting force. Finally, an experiment is carried out to demonstrate that the active isolator is applicable for suppressing the ground vibration.

Numerical and Experimental Investigation of a Single-Axis Parallel Active Vibration Mount for Helicopter Seats Using Vibration Standards

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Amin Fereidooni ◽  
Silas Graham ◽  
Eric Chen ◽  
Viresh Wickramasinghe
Keyword(s):  
Vibration Isolation ◽  
Experimental Results ◽  
Least Mean Square ◽  
Axis Parallel ◽  
Active Vibration ◽  
Iso 2631 ◽  
The Given ◽  
Nonlinear Numerical Model ◽  
Good Agreement ◽  
Helicopter Vibration

Abstract This paper presents the experimental and numerical investigation of a single-axis replicate of a patented multi-axis active vibration isolation seat mount. Following the design of the multi-axis system, this single axis vibration isolation mount uses a flexible elastomer support placed in parallel with an electromagnetic actuator. This mount is designed to reduce the N/rev harmonic vibration of a helicopter using a filtered-X least mean square (FXLMS)-based controller. To improve the efficiency of the FXLMS controller for this application, the ISO-2631-1 Wk filter is added. Employing this modified controller, the experimental setup is tested using a payload mass representative of a 95th percentile pilot. The experimental results confirm the effectiveness of the proposed design in canceling the unwanted helicopter vibration, where the active mount effectively reduces the vibration representative of a Bell-412 helicopter by 69.37% (−10.28 dB, g-rms). In order to develop a better understanding of the problem, the system is also modeled from first principles in simulink. The comparison between the nonlinear numerical model and the experimental results demonstrates a good agreement between the two approaches. Moreover, it is shown that the addition of the ISO-2631-1 Wk filter improves the transient performance of the FXLMS controller for the given helicopter vibration profile.

Application of Compliant Mechanisms to Active Vibration Isolation Systems

2004 ◽  
Author(s):  
Tanakorn Tantanawat ◽  
Zhe Li ◽  
Sridhar Kota
Keyword(s):  
Vibration Isolation ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Vibration Isolator ◽  
External Energy ◽  
Low Frequencies ◽  
Output Amplitude ◽  
Active Vibration ◽  
Isolation Systems ◽  
Active Vibration Isolation

Compliant mechanisms have been designed for various types of applications to transmit desired forces and motions. In this paper, we explore an application of compliant mechanisms for active vibration isolation systems. For this type of application, an actuator and a compliant mechanism are used to cancel undesired disturbance, resulting in attenuated output amplitude. An actuator provides external energy to the system while a compliant mechanism functions as a transmission controlling the amount of displacement transmitted from the actuator to the payload to be isolated. This paper illustrates, based on preliminary results of finite element analyses (FEA), that a compliant mechanism equipped with an actuator can be used as an active vibration isolator to effectively cancel a known sinusoidal displacement disturbance at low frequencies by using a feedforward disturbance compensation control. The nonlinear FEA shows that a sinusoidal displacement disturbance of 6.0 mm amplitude is reduced by 95% at 3.9 Hz and 91% at 35.1 Hz with a sinusoidal displacement controlled input of 0.73 mm amplitude.

Nonlinearity of Maglev Actuator and Adaptive Vibration Control Using Improved FxLMS Algorithm

2013 ◽  
Vol 390 ◽  
pp. 434-439 ◽  
Author(s):  
Yan Li ◽  
Lin He ◽  
Chang Geng Shuai
Keyword(s):  
Vibration Isolation ◽  
Least Mean Square ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Fxlms Algorithm ◽  
Active Vibration ◽  
Spectrum Excitation ◽  
Least Mean Square Algorithm ◽  
Adaptive Vibration Control ◽  
Active Vibration Isolation

Maglev actuator is excellent for active vibration isolation, with non-contact form, low stiffness and rapid response. However, the actuators nonlinearity has to be restrained by the control algorithm. In this paper, the nonlinearity of maglev actuator was studied through theoretical analysis and experiment. An improved multi-channel FxLMS(filtered-x least mean square) algorithm was proposed, which considers the nonlinearity-induced harmonic frequency as extra line-spectrum excitation to control. Experiments showed that the improved FxLMS algorithm could efficiently compensate the nonlinearity of the actuators, thus had better effect when used in active vibration isolation system with non-linear actuators, compared with the traditional FxLMS method.

Adaptive Least-Mean Square Feed-Forward Control With Actuator Saturation by Direct Minimization

2005 ◽  
Author(s):  
Lei Zuo ◽  
Samir A. Nayfeh
Keyword(s):  
Vibration Isolation ◽  
Actuator Saturation ◽  
Ground Vibration ◽  
Lms Algorithm ◽  
Mean Square ◽  
Least Mean Square ◽  
Control Effort ◽  
Isolation System ◽  
Active Vibration ◽  
The Cost

The least-mean squares (LMS) adaptive feedforward algorithm is used widely for vibration and noise cancellation. If reference signals become large enough to saturate that actuators, the filter coefficients in such algorithms can diverge. The leaky LMS method limits the controller effort by augmenting the objective function by a weighted control effort, and is known to attain good performance and avoid growth of filter coefficients for well-chosen weights. We propose an algorithm that seeks to directly minimize the mean-square cost in the presence of saturation. We derive the true stochastic gradient of the cost for systems with saturation with respect to the filter coefficients and obtain an adaptation rule very close to that of the filtered-x algorithm, but in the proposed algorithm, the reference filter is a time-varying modification of the secondary channel. In simulations of an active vibration isolation system with actuator limits subject to random ground vibration, the leaky LMS algorithm attains its best performance with actuation weights small enough to allow significant actuator saturation but large enough to prevent divergence. The proposed algorithm attains performance better that attained by the leaky LMS algorithm, and does not require the selection of weights.

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