scholarly journals A Novel Dynamic Absorber with Variable Frequency and Damping

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Tian Wang ◽  
Ruilan Tian ◽  
Xinwei Yang ◽  
Ziwen Zhang ◽  
Xiaolong Zhang
Keyword(s):  
Coupled System ◽  
Smoothing Parameter ◽  
Current Intensity ◽  
Variable Frequency ◽  
Dynamic Vibration Absorber ◽  
Sd Oscillator ◽  
Dynamic Absorber ◽  
Control Principle ◽  
And Control ◽  
Two Degree Of Freedom

Smoothness and discontinuous (SD) oscillator is a nonlinear oscillator with the variable frequency, whose frequency can be varied with the smoothing parameter. However, how to adjust the smoothing parameter has not been solved in the actual device. In this paper, the shape memory alloy (SMA) is introduced into the SD oscillator to form the SMA-SD oscillator to adjust the smoothing parameters. Combining the SMA-SD oscillator with MRF, a nonlinear dynamic vibration absorber (DVA) with variable frequency and damping is designed. The structure and control principle of the designed DVA is studied to achieve the two variable characteristics simultaneously by adjusting the current intensity. Numerical results on a two-degree-of-freedom coupled system show that the proposed DVA can adapt to different working conditions only by adjusting the current intensity.

Suppression of Vibration by Using Antiresonance Point of a Dynamic Vibration Absorber

2007 ◽  
Author(s):  
Hidetoshi Okaguchi ◽  
Hiroshi Yabuno
Keyword(s):  
Real Time ◽  
Natural Frequency ◽  
Control Method ◽  
Excitation Frequency ◽  
Time Estimation ◽  
Dynamic Vibration Absorber ◽  
Main System ◽  
Wide Range ◽  
Dynamic Absorber ◽  
And Control

The conventional passive dynamic absorber reduces the amplitude of the main system when the natural frequency of the absorber corresponds to the excitation frequency. The dynamic absorber produces two resonance peak. In this paper, we propose a control method of the semi-active dynamic absorber to reduce the amplitude of the main system to zero over the wide range of excitation frequency. The proposed controller has the system of real time estimation of excitation frequency by applying adaptive filter. When the excitation frequency varies, the frequency is estimated by the controller in real time and control signal is generated according to the estimated frequency. As a result, the natural frequency of the absorber is changed in real time and the amplitude of the main system is kept to zero over the wide range of excitation frequency. The performance of the proposed control method is experimentally discussed.

Design and Control of the Double Side Variable Frequency Based Brushless Doubly-Fed Generator System

2021 ◽  
Author(s):  
Yakun Zhou ◽  
Zhongchao Wei ◽  
Xi Chen ◽  
Xuefan Wang ◽  
Guoqing Hu ◽  
...  
Keyword(s):  
Variable Frequency ◽  
Generator System ◽  
Doubly Fed ◽  
Doubly Fed Generator ◽  
And Control ◽  
Side Variable

Fractal Boundary Explorations for a Nonlinear Two Degree-of-Freedom System

2012 ◽  
Author(s):  
Benjamin A. M. Owens ◽  
Brian P. Mann
Keyword(s):  
Initial Conditions ◽  
Coupled System ◽  
Basins Of Attraction ◽  
Degree Of Freedom ◽  
Fractal Boundary ◽  
Final State ◽  
Potential Wells ◽  
Mechanical Coupling ◽  
Mass Spring ◽  
Two Degree Of Freedom

This paper explores a two degree-of-freedom nonlinearly coupled system with two distinct potential wells. The system consists of a pair of linear mass-spring-dampers with a non-linear, mechanical coupling between them. This nonlinearity creates fractal boundaries for basins of attraction and forced well-escape response. The inherent uncertainty of these fractal boundaries is quantified for errors in the initial conditions and parameter space. This uncertainty relationship provides a measure of the final state and transient sensitivity of the system.

Design a PLC-Based Variable-Frequency Governing Pressure-Constant Water-Supply Control System

2014 ◽  
Vol 1044-1045 ◽  
pp. 755-758
Author(s):  
Xin Hui Yang
Keyword(s):  
Control System ◽  
Water Supply ◽  
Pressure Sensors ◽  
Variable Frequency ◽  
Pipe Network ◽  
Monitoring And Control ◽  
Control Software ◽  
Industrial Control ◽  
Time Basis ◽  
And Control

This paper provides a design for a PLC-based, variable-frequency governing, pressure-constant, automatic water-supply control system. This design is based on the current situations at the water supply plants found in small and medium cities in China. In this control system, the pressure signal across the pipe network is acquired by pressure sensors and then transmitted to PID modules in the PLC in order to control switching between pump motors. At the same time, the PLC is connected with a personal computer for industrial control purposes. On this computer, monitoring and control software has been installed in order to monitor and control the pressure-constant water-supply system on a real-time basis.

Two-Degree-of-Freedom Helicopter Closed-Loop Identification through a Cascade Controller

2011 ◽  
Vol 403-408 ◽  
pp. 4649-4658 ◽  
Author(s):  
Pouya Ghalei ◽  
Alireza Fatehi ◽  
Mohamadreza Arvan
Keyword(s):  
Closed Loop ◽  
Flight Simulation ◽  
Degree Of Freedom ◽  
Input Output ◽  
Closed Loop Identification ◽  
Practical Algorithm ◽  
Nonlinear Autoregressive Model ◽  
And Control ◽  
Nonlinear Autoregressive ◽  
Two Degree Of Freedom

Input-Output data modeling using multi layer perceptron networks (MLP) for a laboratory helicopter is presented in this paper. The behavior of the two degree-of-freedom platform exemplifies a high order unstable, nonlinear system with significant cross-coupling between pitch and yaw directional motions. This paper develops a practical algorithm for identifying nonlinear autoregressive model with exogenous inputs (NARX) and nonlinear output error model (NOE) through closed loop identification. In order to collect input-output identifier pairs, a cascade state feedback (CSF) controller is introduced to stabilize the helicopter and after that the procedure of system identification is proposed. The estimated models can be utilized for nonlinear flight simulation and control and fault detection studies.

The Swirling Pendulum: Conceptualization, Modeling, Equilibria and Control Synthesis

2020 ◽  
Author(s):  
Sujay D. Kadam ◽  
Utsav Shah ◽  
Alrick D’Souza ◽  
Prajwal Gowdru Shanthamurthy ◽  
Nidhish Raj ◽  
...  
Keyword(s):  
Equilibrium Points ◽  
Point Of View ◽  
Control Synthesis ◽  
Test Bed ◽  
Lagrange’S Equation ◽  
Systems And Control ◽  
System Inversion ◽  
And Control ◽  
Two Degree Of Freedom ◽  
Present Simulation

Abstract This paper introduces the swirling pendulum, a two-link, two degree-of-freedom mechanism which is under-actuated and has an unusual non-planar coupling with axis of rotation of the two links being perpendicular to each other. The swirling pendulum mechanism, while being simple to mathematically represent and easy to physically construct, exhibits several properties like loss of inertial coupling, loss of relative degree, multiple stable and unstable equilibrium points. These properties are unique as well as interesting from dynamics and controls point of view which make the swirling pendulum an excellent test-bed for testing various ideas in control and demonstrating several notions associated with systems and control theory. In this paper, we discuss the modeling of the swirling pendulum mechanism based on Lagrange’s equation along with an analysis related to equilibrium points and their stability. We also present simulation results for regulatory as well as tracking control tasks through simulations on a non-linear model using control methods like LQR, lead compensator and system inversion-based control to demonstrate the utility of the proposed mechanism in the area of systems, control and dynamics. Furthermore, we also discuss experimental results for controls applied on a real-time hardware setup.

Dynamic Vibration Absorber for a Ropeway Carrier

1997 ◽  
Author(s):  
Hiroshi Matsuhisa ◽  
Osamu Nishihara
Keyword(s):  
Natural Frequency ◽  
Damping Ratio ◽  
Vibration Absorber ◽  
Moving Mass ◽  
Dynamic Vibration Absorber ◽  
Damping Effect ◽  
The World ◽  
Dynamic Absorber ◽  
First Time ◽  
Suspended Bridge

Abstract Ropeways such as gondola lifts have attracted increasing interest as a means of transportation in cities. However, swing of ropeway carriers is easily caused by wind, and usually a ropeway cannot operate if the wind velocity exceeds about 15m/s. The study of how to reduce the wind-induced swing of ropeway carriers has attracted many researchers. It had been said that it was impossible to reduce the vibration of pendulum type structures such as ropeway carriers by a dynamic absorber. But in 1993, Matsuhisa showed that the swing of carrier can be reduced by a dynamic absorber if it is located far above or below from the center of oscillation. Based on this finding, a dynamic absorber composed of a moving mass on an arc-shaped track was designed for practical use, and it was installed in chairlift-type carriers and gondola type carriers in snow skiing sites in Japan in 1995 for the first time in the world. It has been shown that a dynamic absorber with the weight of one tenth of the carrier can reduce the swing to half. The liquid dynamic absorber was also investigated. It has the same damping effect as the conventional solid absorber. It is easy to adjust the natural frequency and the damping ratio, and the structure is simple. Therefore, it will be applied for not only ropeway carriers but also ships and rope suspended bridge and others.

Development and Design of the Dynamic Vibration Absorber Using Magneto-Rheological Elastomer for the Weight and Power Consumption Saving

2019 ◽  
Author(s):  
Osamu Terashima ◽  
Mika Nakata ◽  
Toshihiko Komatsuzaki
Keyword(s):  
Magnetic Field ◽  
Power Consumption ◽  
Natural Frequency ◽  
Damping Ratio ◽  
Wide Band ◽  
Test Results ◽  
Dynamic Vibration Absorber ◽  
Small Power ◽  
Dynamic Absorber ◽  
Magneto Rheological

Abstract In this study, a broadband frequency tunable dynamic absorber was designed and fabricated based on the primary design principle of a mass damper. A magneto-rheological elastomer that can change the relative stiffness when an external magnetic field is applied was used to control the natural frequency of the movable mass of the absorber. A coil to generate the magnetic field was also used as a movable mass to decrease the total weight and to create a constant closed loop of the magnetic force. The hammer impact test results show that the present absorber could change its natural frequency with minimal electric power and had a constant damping ratio. Experimental results of vibration absorbing of an acrylic flat plate show that the proposed absorber could change the natural frequency of the movable mass and reduce the vibration over a wide band by constantly applying the optimum current to the coil in the device with a small power consumption (less than 10 W). Therefore, the proposed absorber works effectively. Further, a technique to determine the electric current applied to the coil automatically based on the phase difference of the vibrational acceleration of the movable mass and the vibrating objective was also presented.

scholarly journals The Coupled Orbit-Attitude Dynamics and Control of Electric Sail in Displaced Solar Orbits

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Mingying Huo ◽  
He Liao ◽  
Yanfang Liu ◽  
Naiming Qi
Keyword(s):  
Linear Quadratic Regulator ◽  
Coupled System ◽  
Control Force ◽  
Attitude Dynamics ◽  
Voltage Distribution ◽  
Linear Quadratic ◽  
Displaced Orbit ◽  
Dynamics And Control ◽  
And Control ◽  
Small Torque

Displaced solar orbits for spacecraft propelled by electric sails are investigated. Since the propulsive thrust is induced by the sail attitude, the orbital and attitude dynamics of electric-sail-based spacecraft are coupled and required to be investigated together. However, the coupled dynamics and control of electric sails have not been discussed in most published literatures. In this paper, the equilibrium point of the coupled dynamical system in displaced orbit is obtained, and its stability is analyzed through a linearization. The results of stability analysis show that only some of the orbits are marginally stable. For unstable displaced orbits, linear quadratic regulator is employed to control the coupled attitude-orbit system. Numerical simulations show that the proposed strategy can control the coupled system and a small torque can stabilize both the attitude and orbit. In order to generate the control force and torque, the voltage distribution problem is studied in an optimal framework. The numerical results show that the control force and torque of electric sail can be realized by adjusting the voltage distribution of charged tethers.

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