scholarly journals Experiment and Analysis of Active Vibration Suppression via an Absorber with a Tunable Delay

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Yixia Sun
Keyword(s):  
Vibration Suppression ◽  
Transfer Functions ◽  
Experimental Studies ◽  
Coupled System ◽  
Gain Coefficient ◽  
Feedback Gain ◽  
Primary System ◽  
Active Vibration ◽  
The Stability ◽  
Proper Values

A time-delayed absorber is utilized to suppress the vibration of a primary system excited by a simple harmonic force. The inherent and intentional time delays in the feedback control loop are taken into consideration. The value of the former is fixed, while the value of the latter is tunable in the controller. To begin with, the mechanical model of the system is established and the acceleration transfer functions of the system are derived. Consequently, the stability analysis of the coupled system is carried out. Finally, the experimental studies on the performance of the time-delayed absorber are conducted. Both experimental and theoretical results show that the time-delayed absorber with proper values of feedback gain coefficient and intentional time delay greatly suppresses the vibration of the primary system. The numerical results validate the correctness of the experimental and theoretical ones.

scholarly journals Evaluation of the Autoparametric Pendulum Vibration Absorber for a Duffing System

2008 ◽  
Vol 15 (3-4) ◽  
pp. 355-368 ◽  
Author(s):  
Benjamın Vazquez-Gonzalez ◽  
Gerardo Silva-Navarro
Keyword(s):  
Frequency Response ◽  
Fixed Points ◽  
Multiple Scales ◽  
Coupled System ◽  
Vibration Absorber ◽  
Primary System ◽  
Duffing System ◽  
Approximate Frequency ◽  
The Stability ◽  
Cubic Stiffness

In this work we study the frequency and dynamic response of a damped Duffing system attached to a parametrically excited pendulum vibration absorber. The multiple scales method is applied to get the autoparametric resonance conditions and the results are compared with a similar application of a pendulum absorber for a linear primary system. The approximate frequency analysis reveals that the nonlinear dynamics of the externally excited system are suppressed by the pendulum absorber and, under this condition, the primary Duffing system yields a time response almost equivalent to that obtained for a linear primary system, although the absorber frequency response is drastically modified and affected by the cubic stiffness, thus modifying the jumps defined by the fixed points. In the absorber frequency response can be appreciated a good absorption capability for certain ranges of nonlinear stiffness and the internal coupling is maintained by the existing damping between the pendulum and the primary system. Moreover, the stability of the coupled system is also affected by some extra fixed points introduced by the cubic stiffness, which is illustrated with several amplitude-force responses. Some numerical simulations of the approximate frequency responses and dynamic behavior are performed to show the steady-state and transient responses.

Active Vibration Suppression With Time Delayed Feedback

2003 ◽  
Vol 125 (3) ◽  
pp. 384-388 ◽  
Author(s):  
Rifat Sipahi ◽  
Nejat Olgac
Keyword(s):  
Stability Analysis ◽  
Time Delay ◽  
Vibration Suppression ◽  
Linear Time ◽  
Direct Method ◽  
System Stability ◽  
Delayed Systems ◽  
Active Vibration Suppression ◽  
Active Vibration ◽  
The Stability

Various active vibration suppression techniques, which use feedback control, are implemented on the structures. In real application, time delay can not be avoided especially in the feedback line of the actively controlled systems. The effects of the delay have to be thoroughly understood from the perspective of system stability and the performance of the controlled system. Often used control laws are developed without taking the delay into account. They fulfill the design requirements when free of delay. As unavoidable delay appears, however, the performance of the control changes. This work addresses the stability analysis of such dynamics as the control law remains unchanged but carries the effect of feedback time-delay, which can be varied. For this stability analysis along the delay axis, we follow up a recent methodology of the authors, the Direct Method (DM), which offers a unique and unprecedented treatment of a general class of linear time invariant time delayed systems (LTI-TDS). We discuss the underlying features and the highlights of the method briefly. Over an example vibration suppression setting we declare the stability intervals of the dynamics in time delay space using the DM. Having assessed the stability, we then look at the frequency response characteristics of the system as performance indications.

Design and Stability Analysis of Delayed Resonator With Acceleration Feedback

2013 ◽  
Author(s):  
Tomáš Vyhlídal ◽  
Nejat Olgac ◽  
Vladimír Kučera
Keyword(s):  
Vibration Suppression ◽  
Dynamics Analysis ◽  
Stability Boundaries ◽  
Single Degree Of Freedom ◽  
Stability Margins ◽  
Single Degree ◽  
Active Vibration Suppression ◽  
Acceleration Feedback ◽  
Active Vibration ◽  
The Stability

This paper deals with the problem of active vibration suppression using the concept of delayed resonator with acceleration feedback. A complete dynamics analysis of the resonator and its coupling with a single degree of freedom mechanical system are performed. It is shown that due to presence of a delay in the derivative feedback, the dynamics of the resonator itself, as well as the dynamics of its coupling with the system are of neutral character. Subsequently, the spectral approach is used to obtain the stability boundaries in the space of the resonator parameters. Both, analytical and numerical methods are employed in the analysis. As the contributions, we display a methodology to determine the resonator parameters in order to guarantee desirable functioning of the resonator and to provide safe stability margins. An example is included to demonstrate these analytical results.

scholarly journals Agile Attitude Maneuvers with Active Vibration-suppression for Flexible-spacecraft

2021 ◽  
Author(s):  
Zhang Jianqiao ◽  
Xianglong Kong ◽  
Chuang Liu ◽  
Qing Deng
Keyword(s):  
Vibration Suppression ◽  
Sliding Mode ◽  
Lyapunov Stability Theory ◽  
Flexible Spacecraft ◽  
Robust Controller ◽  
Adaptive Sliding Mode Controller ◽  
Control Moment ◽  
Active Vibration Suppression ◽  
Active Vibration ◽  
The Stability

Abstract This paper addresses the agile attitude stabilization maneuver control of flexible-spacecraft using control moment gyros (CMGs) in the absence of modal information. Here, piezoelectric actuators are employed to actively suppress the vibration of flexible appendages. Both the attitude dynamics and the proposed robust controller are globally developed on the Special Orthogonal Group SO(3), avoiding ambiguities and singularities associated with other attitude representations. More specifically, an observer is first designed to estimate the modal information of vibration. A robust control law is developed by synthesizing a proportional derivative (PD) controller, an adaptive sliding mode controller, and an active vibration-suppression controller, which use the information of the estimated structural modes. The stability of the closed-loop system is proved using Lyapunov stability theory. Finally, numerical examples are performed to show the effectiveness of the proposed method.

A Unified Transfer Function (UTF) Approach for the Modeling and Stability Analysis of Long Slender Bars in 3-D Turning Operations

1993 ◽  
Vol 115 (2) ◽  
pp. 193-204 ◽  
Author(s):  
I. N. Tansel
Keyword(s):  
Stability Analysis ◽  
Transfer Function ◽  
Transfer Functions ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Tool Geometry ◽  
Turning Operations ◽  
Chip Area ◽  
The Stability ◽  
Unique Relationship

A new approach is introduced to model 3-D turning operations that are used for the stability analysis of long slender bars. This approach utilizes the unique relationship between externally created feed direction tool displacements (input) and the resultant thrust direction workpiece vibrations (output) to estimate stability limits in three-dimensional turning operations from the data of a single dynamic cutting test. In this paper, this unique relationship is referred to as the “Unified Transfer Function ” (UTF) and its expressions are derived from conventional cutting and structural dynamics transfer functions. For the stability analysis, the uncut chip area variations of oblique cutting are represented by a linear model having different coefficients at different depths of cuts. These coefficients are found by using a tool geometry simulation program. An iterative procedure is developed for the stability analysis. The proposed approach considers in-process structural and cutting dynamics and can be automatically implemented without any input from the operator for the traverse turning of a long slender bar. Experimental studies have validated the proposed modeling and stability analysis techniques. The UTFs can also be used to monitor machine tool structure, tool wear, and the machinability of the material.

scholarly journals A single-step identification strategy for the coupled TITO process using fractional calculus

2021 ◽  
pp. 014233122199273
Author(s):  
Kajal Kothari ◽  
Utkal Mehta ◽  
Ravneel Prasad
Keyword(s):  
Transfer Functions ◽  
Mimo System ◽  
Operational Matrix ◽  
Experimental Studies ◽  
Algebraic Approach ◽  
Coupled System ◽  
Single Step ◽  
Accurate Estimation ◽  
Complete Control ◽  
Identification Strategy

The reliable performance of a complete control system depends on accurate model information being used to represent each subsystem. The identification and modelling of multivariable systems are complex and challenging due to cross-coupling. Such a system may require multiple steps and decentralized testing to obtain full system models effectively. In this paper, a direct identification strategy is proposed for the coupled two-input two-output (TITO) system with measurable input–output signals. A well-known closed-loop relay test is utilized to generate a set of inputs–outputs data from a single run. Based on the collected data, four individual fractional-order transfer functions, two for main paths and two for cross-paths, are estimated from single-run test signals. The orthogonal series-based algebraic approach is adopted, namely the Haar wavelet operational matrix, to handle the fractional derivatives of the signal in a simple manner. A single-step strategy yields faster identification with accurate estimation. The simulation and experimental studies depict the efficiency and applicability of the proposed identification technique. The demonstrated results on the twin rotor multiple-input multiple-output (MIMO) system (TRMS) clearly reveal that the presented idea works well with the highly coupled system even in the presence of measurement noise.

MIMO-FEA Active Vibration Suppression of a Satellite Using an Adaptive Composite Thruster Platform

Aerospace ◽  
2006 ◽  
Author(s):  
Mehrdad N. Ghasemi-Nejhad ◽  
Nicolas Antin
Keyword(s):  
Finite Element ◽  
Position Control ◽  
Vibration Suppression ◽  
Complex Geometry ◽  
External Disturbance ◽  
Coupled System ◽  
Element Analysis ◽  
Active Vibration Suppression ◽  
Active Vibration ◽  
And Function

Adaptive or intelligent structures which have the capability for sensing and responding to their environment promise a novel approach to satisfying the stringent performance requirements of future space missions. This research focuses on a finite element analysis (FEA) multi-input-multi-output (MIMO) approach for vibration suppression and precision position control of a satellite thruster and its structure, due to the thruster-firing, employing an intelligent composite thruster platform. This smart platform connects the thruster to the structure of the satellite and has three active struts and one active central support with piezoelectric stacks as actuators, and each has a sensor at its base. It also has an active circular composite plate as the top device plate with nine embedded piezoelectric patches that six of them are back-to-back and function as three actuators pairs and three of them are placed next to the bottom actuators and function as sensors. Here, the predominant modes of the structure are first determined. In the FEA method, a finite element harmonic analysis was employed to develop a vibration suppression scheme, which was then used to study the vibration control of the satellite structure using the vibration suppression capabilities of the intelligent platform mounted on the satellite. In this approach, the responses of the structure to a unit external force as well as unit internal piezoelectric control voltages are first determined, individually. The responses are then assembled in a system of equation as a coupled system and then solved simultaneously to determine the control voltages and their respective phases for the system actuators for a given external disturbance. Next, this technique was applied to the vibration suppression of the satellite frame as well as its thruster simultaneously as a coupled problem and the results are discussed. This approach is an effective technique for the design of smart structures with complex geometry to study their active vibration suppression capabilities and effectiveness. The entire system has ten actuators: four piezoelectric stack actuators and three pairs of piezoelectric patch actuators.

Bioaeroservoelastic Analysis of Involuntary Rotorcraft-Pilot Interaction

2014 ◽  
Vol 9 (3) ◽  
Author(s):  
Pierangelo Masarati ◽  
Giuseppe Quaranta
Keyword(s):  
Muscle Activation ◽  
Inverse Dynamics ◽  
Transfer Functions ◽  
Biomechanical Model ◽  
Coupled System ◽  
Multibody Modeling ◽  
Activation Patterns ◽  
Pilot Model ◽  
The Stability ◽  
Muscular Activation

This work presents the integration of a detailed biomechanical model of the arm of a helicopter pilot and an equivalently detailed aeroservoelastic model of a helicopter, resulting in what has been called a ‘bioaeroservoelastic’ analysis. The purpose of this analysis is to investigate potential adverse interactions, called rotorcraft-pilot couplings, between the aeroservoelastic system and the controls involuntarily introduced by the pilot into the control system in response to rotorcraft vibrations transmitted to the pilot through the cockpit: the so-called biodynamic feedthrough. The force exerted by the pilot on the controls results from the activation of the muscles of the arms according to specific patterns. The reference muscular activation value as a function of the prescribed action on the controls is computed using an inverse kinetostatics/inverse dynamics approach. A first-order quasi-steady correction is adopted to mimic the reflexive contribution to muscle activation. Muscular activation is further augmented by activation patterns that produce elementary actions on the control inceptors. These muscular activation patterns, inferred using perturbation analysis, are applied to control the aircraft through the pilot's limbs. The resulting biomechanical pilot model is applied to the aeroservoelastic analysis of a helicopter model expressly developed within the same multibody modeling environment to investigate adverse rotorcraft pilot couplings. The model consists of the detailed aeroelastic model of the main rotor, using nonlinear beams and blade element/momentum theory aerodynamics, a component mode synthesis model of the airframe structural dynamics, and servoactuator dynamics. Results in terms of the stability analysis of the coupled system are presented in comparison with analogous results obtained using biodynamic feedthrough transfer functions identified from experimental data.

A Mechanical Approach to the Design of Independent Modal Space Control for Vibration Suppression

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
S. Cinquemani ◽  
F. Resta
Keyword(s):  
Vibration Suppression ◽  
Dynamic Performance ◽  
Active Vibration Control ◽  
Flexible System ◽  
Damping Matrix ◽  
Modal Damping ◽  
Active Vibration ◽  
The Stability ◽  
Modal Space ◽  
Modal Controller

Many systems have, by their nature, a small damping and therefore they are potentially subjected to dangerous vibration phenomena. The aim of active vibration control is to contain this phenomenon, improve the dynamic performance of the system, and increase its fatigue strength. A way to reach this goal is to increase the system damping, preferably without changing its natural frequencies and vibration modes. In the past decades this has been achieved by developing the well-known independent modal space control (IMSC) technique. The paper describes a new approach to the synthesis of a modal controller to suppress vibrations in structures. It turns from the traditional formulation of the problem and it demonstrates how the performance of the controller can be evaluated through the analysis of the modal damping matrix of the controlled system. The ability to easily manage this information allows us to synthesize an efficient modal controller. Furthermore, it enables us to easily evaluate the stability of the control, the effects of spillover, and the consequent effectiveness in reducing vibration. Theoretical aspects are supported by experimental applications on a large flexible system.

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