Modal Analysis of High-Speed Parallel Manipulator with Flexible Links

2016 ◽  
Vol 826 ◽  
pp. 8-14 ◽  
Author(s):  
Zheng Sheng Chen ◽  
Ming Liu ◽  
Min Xiu Kong ◽  
Chen Ji
Keyword(s):  
Modal Analysis ◽  
Parallel Manipulator ◽  
High Speed ◽  
Structural Model ◽  
Lagrange Equation ◽  
Flexible Link ◽  
Flexible Coupling ◽  
Flexible Links ◽  
Coupling Technique ◽  
Abaqus Model

The modal analysis was carried out to investigate the proposed improved curvature based finite element method (ICFE) for parallel manipulator with flexible links. The flexible link was discretizatied with ICFE first, and with the proposed rigid-flexible coupling technique, the flexible displacement of the moving platform and passive links was obtained, then through Lagrange equation, the structural model was derived. At last, to investigate the accuracy and efficiency of the ICFE and rigid-flexible coupling technique, modal analysis of ICFE model with different nodes and comparison studies with CFE and the ABAQUS model was carried out.

Dynamics of a Flexible-Link Planar Parallel Manipulator in Cartesian Space

1994 ◽  
Author(s):  
Abbas Fattah ◽  
Arun K. Misra ◽  
Jorge Angeles
Keyword(s):  
Parallel Manipulator ◽  
High Speed ◽  
Inverse Dynamics ◽  
Equations Of Motion ◽  
Flexible Link ◽  
End Effector ◽  
Joint Torques ◽  
Flexible Links ◽  
Cartesian Space ◽  
Planar Parallel Manipulator

Abstract The subject of this paper is the modeling and simulation of a flexible-link planar parallel manipulator in Cartesian space. Given a desired end-effector motion, the inverse kinematics and inverse dynamics of a rigid-link model of the parallel manipulator is used to obtain actuated joint torques. The actual end-effector motion and vibration of the flexible links are obtained using simulation (direct dynamics) for the flexible-link manipulator. Finite elements are used to model the flexible links, while the Euler-Lagrange formulation is used to derive the equations of motion of the uncoupled links. The equations of motion of all the links are assembled to obtain the governing equations for the entire system. The methodology of the natural orthogonal complement, which has been previously applied to flexible-link systems with open-chain structures, is used here to eliminate the constraint forces. Finally, geometric nonlinearities in elastic deformations, which are very important in high-speed operations, are also considered.

MULTI-MODE VIBRATION CONTROL AND POSITION ERROR ANALYSIS OF PARALLEL MANIPULATOR WITH MULTIPLE FLEXIBLE LINKS

2010 ◽  
Vol 34 (2) ◽  
pp. 197-213 ◽  
Author(s):  
Xuping Zhang ◽  
James K. Mills ◽  
William L. Cleghorn
Keyword(s):  
Vibration Control ◽  
Parallel Manipulator ◽  
Position Error ◽  
Flexible Link ◽  
Flexible Links ◽  
Position Errors ◽  
Mode Vibration ◽  
Moving Platform ◽  
Multi Mode ◽  
Modal Space

This paper presents multi-mode vibration control and analysis of moving platform position errors of a planar 3-PRR parallel manipulator with three flexible intermediate links using PZT transducers. The active vibration controller is designed in modal space with modal filters and modal synthesizers determined from the flexible link vibration characteristics. Estimation of the moving platform position error is conducted using measurements of the flexible link deflection from PZT sensors mounted on the flexible intermediate links. An effective strategy for determining the control gains to reduce the vibrations of higher order modes is proposed through modification of the independent modal space control (IMSC) method. The proposed independent modal control strategy is experimentally implemented with first two modes targeted for control on a parallel manipulator with multiple flexible links. The experimental results show that the vibrations of the first two modes are effectively suppressed, and the position error of the moving platform is substantially reduced.

Singular perturbation adaptive control and vibration suppression of free-flying flexible space manipulators

2014 ◽  
Vol 229 (11) ◽  
pp. 1989-1997 ◽  
Author(s):  
Xiao Yan Yu ◽  
Li Chen
Keyword(s):  
Adaptive Control ◽  
Singular Perturbation ◽  
Lagrange Equation ◽  
Momentum Conservation ◽  
Flexible Manipulator ◽  
Physical Parameters ◽  
Flexible Link ◽  
Linear Quadratic ◽  
Flexible Links ◽  
Space Manipulators

Singular perturbation adaptive control is designed for free-flying space manipulators with multiple flexible links and unknown physical parameters. The dynamical Lagrange equation was established based on assumed mode technique and linear momentum conservation theory. A singular perturbation model has been formulated and used for designing a reduced-order controller. This controller consisted of a slow control component and a fast control component. An adaptive control law was constructed for the slow counterpart of the flexible manipulator. The flexible-link fast subsystem controller would damp out the vibrations of flexible links by optimal linear quadratic regulator method. Numerical simulations by undertaking a computer simulation of a two-flexible-link space manipulator using the fourth-order Runge–Kutta integration method showed that the link vibrations had been stabilized effectively with good tracking performance.

Rigid versus Flexible Link Dynamic Analysis of a 3DOF Delta Type Parallel Manipulator

2015 ◽  
Vol 762 ◽  
pp. 101-106 ◽  
Author(s):  
Nadia Ramona Cretescu ◽  
Mircea Neagoe
Keyword(s):  
Dynamic Analysis ◽  
Numerical Simulations ◽  
Parallel Manipulator ◽  
Numerical Models ◽  
Parallel Robot ◽  
Flexible Link ◽  
Flexible Links ◽  
Delta Type ◽  
Adams Software

This paper presents a comparative kinematic and dynamic analysis of a Delta parallel robot based on numerical simulations of the rigid vs. flexible links robot models. The flexible links numerical models are derived using AutoFlex module of Adams software. Finally, the conclusions regarding the obtained results useful in manipulator constructive design are presented.

Influence of Multiphysical Effects on the Dynamics of the High Speed Mini Rotors—Part II: Results

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Emre Dikmen ◽  
Peter J. M. van der Hoogt ◽  
André de Boer ◽  
Ronald G. K. M. Aarts
Keyword(s):  
Modal Analysis ◽  
Dynamic Behavior ◽  
High Speed ◽  
Structural Model ◽  
Natural Frequencies ◽  
Experimental Setup ◽  
Flexible Supports ◽  
The Stability ◽  
Surrounding Fluid ◽  
Theoretical Results

In Part I of this work, a theoretical analysis showed that the surrounding air in the closed confinement between rotor and casing has a significant effect on the dynamic behavior of high speed minirotors. In order to validate the developed theoretical model, an experimental setup is designed and the dynamic behavior of the rotor with medium gap confinement is studied. The experimental setup has flexible supports, which consist of beams with adjustable length. The support stiffness is changed by altering the beam length. Modal analysis of the rotor is done in free-free conditions in order to test the capability of the rotordynamic model without the supports and multiphysical effects. The experimental and simulation results agree well with a difference of 1%. Then modal analysis of the whole structure is done at standstill and during operation in the absence of the casing. In this way, multiphysical effects are eliminated and only support effects on the dynamics of the structure are observed. The supports appear to have significant effect on the natural frequencies of the flexural modes of the system. Different support modeling techniques are studied and adequate equivalent models are obtained. These models are then implemented into the structural model of the rotor. Finally, multiphysical effects are tested at different speeds with different support stiffnesses. Experiments are performed with and without the casing for determining the change in the natural frequencies and onset of instability. The surrounding fluid has a significant effect on the stability of the system while the natural frequencies do not change significantly. The experimental and theoretical results are in fair agreement for predicting the natural frequencies and the onset of instability.

scholarly journals Full-Field Operational Modal Analysis of an Aircraft Composite Panel from the Dynamic Response in Multi-Impact Test

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1602
Author(s):  
Ángel Molina-Viedma ◽  
Elías López-Alba ◽  
Luis Felipe-Sesé ◽  
Francisco Díaz
Keyword(s):  
Modal Analysis ◽  
Energy Absorption ◽  
High Speed ◽  
Operational Modal Analysis ◽  
Modal Identification ◽  
Image Correlation ◽  
Composite Panel ◽  
Impact Excitation ◽  
Full Field ◽  
The Impact

Experimental characterization and validation of skin components in aircraft entails multiple evaluations (structural, aerodynamic, acoustic, etc.) and expensive campaigns. They require different rigs and equipment to perform the necessary tests. Two of the main dynamic characterizations include the energy absorption under impact forcing and the identification of modal parameters through the vibration response under any broadband excitation, which also includes impacts. This work exploits the response of a stiffened aircraft composite panel submitted to a multi-impact excitation, which is intended for impact and energy absorption analysis. Based on the high stiffness of composite materials, the study worked under the assumption that the global response to the multi-impact excitation is linear with small strains, neglecting the nonlinear behavior produced by local damage generation. Then, modal identification could be performed. The vibration after the impact was measured by high-speed 3D digital image correlation and employed for full-field operational modal analysis. Multiple modes were characterized in a wide spectrum, exploiting the advantages of the full-field noninvasive techniques. These results described a consistent modal behavior of the panel along with good indicators of mode separation given by the auto modal assurance criterion (Auto-MAC). Hence, it illustrates the possibility of performing these dynamic characterizations in a single test, offering additional information while reducing time and investment during the validation of these structures.

Kinematic characteristics of longitudinal double folding wings

2021 ◽  
pp. 1-25
Author(s):  
L. Tiegang ◽  
C. Guoguang ◽  
L. Shuai
Keyword(s):  
Angular Velocity ◽  
Structural Model ◽  
Initial Conditions ◽  
Aerodynamic Force ◽  
Model Simulation ◽  
Lagrange Equation ◽  
Grid Method ◽  
Weapon Systems ◽  
Folding Wing ◽  
Double Folding

ABSTRACT A folding wing is a tactical missile launching device that needs to be miniaturised to facilitate storage, transportation, and launching; save missile and transportation space; and improve the combat capability of weapon systems. This study investigates the aeroelastic characteristics of the secondary longitudinal folding wing during the unfolding process. First, the Lagrange equation is used to establish the structural dynamics model of the folding wing, the kinematics characteristics during the deformation process are analysed, and the unfolding movement of the folding wing is obtained using the dynamic equations in the process. Then, the generalised unsteady aerodynamic force is calculated using the dipole grid method, and the multi-body dynamics equation of the folding wing is obtained. The initial angular velocity required for the deployment of the folding wing is analysed through structural model simulation, and the influence of the initial angular velocity on the opening process is studied. Finally, aeroelastic flutter analysis is performed on the folding wing, and the physical model of the folding wing verified experimentally. Results show that the type of aeroelastic response is sensitive to the initial conditions and the way the folding wing opens.

Research on Internet-Based Reconfigurable Distance Mechanical System Fault Diagnosis

2011 ◽  
Vol 52-54 ◽  
pp. 109-114
Author(s):  
Yun Jie Xu
Keyword(s):  
Fault Diagnosis ◽  
Mechanical System ◽  
High Speed ◽  
Structural Model ◽  
Component Technology ◽  
The Internet ◽  
Diagnostic Systems ◽  
Diagnosis System ◽  
J2ee Framework ◽  
Fault Diagnosis System

In order to meet requirements of increasingly high-speed, large and intelligent mechanical equipments on fault diagnosis, the Internet-based reconfigurable mechanical system fault diagnosis program was presented. The overall structure and networking schema of distance mechanical fault diagnosis system were analyzed, and the distance fault diagnosis network model based on J2EE framework was also described. The structural model and reconfigurable manner of the reconfigurable distance diagnosis system was provided, which used CORBA component technology to achieve reconfiguration. The detail steps of system that take some type of diesel engine as diagnosis object was described, and the intelligent diagnosing methods were also researched. The Internet-based fault diagnosis technology effectively improves the efficiency and accuracy of diagnostic systems.

The Use of Modan 3D in Experimental Modal Analysis

2013 ◽  
Vol 486 ◽  
pp. 36-41 ◽  
Author(s):  
Róbert Huňady ◽  
František Trebuňa ◽  
Martin Hagara ◽  
Martin Schrötter
Keyword(s):  
Modal Analysis ◽  
Vibration Analysis ◽  
High Speed ◽  
Mechanical Vibration ◽  
Steel Sample ◽  
Experimental Modal Analysis ◽  
Image Correlation ◽  
Optical Methods ◽  
Mode Shapes ◽  
Vibration Modes

Experimental modal analysis is a relatively young part of dynamics, which deals with the vibration modes identification of machines or their parts. Its development has started since the beginning of the eighties, when the computers hardware equipment has improved and the fast Fourier transform (FFT) could be used for the results determination. Nowadays it provides an uncountable set of vibration analysis possibilities starting with conventional contact transducers of acceleration and ending with modern noncontact optical methods. In this contribution we mention the use of high-speed digital image correlation by experimental determination of mode shapes and modal frequencies. The aim of our work is to create a program application called Modan 3D enabling the performing of experimental modal analysis and operational modal analysis. In this paper the experimental modal analysis of a thin steel sample performed with Q-450 Dantec Dynamics is described. In Modan 3D the experiment data were processed and the vibration modes were determined. The reached results were verified by PULSE modulus specialized for mechanical vibration analysis.

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