COUPLING EFFECT OF FLEXIBLE JOINT AND FLEXIBLE LINK ON DYNAMIC SINGULARITY OF FLEXIBLE MANIPULATOR

2008 ◽  
Vol 21 (01) ◽  
pp. 9 ◽  
Author(s):  
Zhihui GAO
Keyword(s):  
Coupling Effect ◽  
Flexible Manipulator ◽  
Flexible Link ◽  
Flexible Joint

Resonance Analysis of Manipulators with Flexible Link and Flexible Joint

2011 ◽  
Vol 383-390 ◽  
pp. 2868-2874
Author(s):  
Zhi Hui Gao ◽  
Yu Shu Bian
Keyword(s):  
Motion Planning ◽  
Structure Design ◽  
Flexible Manipulator ◽  
Dynamic Equations ◽  
Flexible Link ◽  
Flexible Joint ◽  
Joint Flexibility ◽  
Resonance Analysis ◽  
Link Flexibility ◽  
Main Factors

Worse than common vibration, resonance is a form of severe vibration. It is very important and useful to know what factors and conditions can result in resonance of flexible manipulators, when both link flexibility and joint flexibility are taken into account. In this paper, resonance analysis of the flexible manipulator with both link flexibility and joint flexibility is studied. Based on the flexible dynamic equations, main factors resulting in resonance of the flexible manipulator are analyzed. Furthermore, several conditions exciting resonance are derived and verified with numerical simulations. These conclusions are helpful to predict resonance and useful to the structure design and motion planning for a flexible manipulator to evade resonance

Coupling Effects in a Manipulator With Both a Flexible Link and Joint

1994 ◽  
Vol 116 (4) ◽  
pp. 826-831 ◽  
Author(s):  
F. Xi ◽  
R. G. Fenton ◽  
B. Tabarrok
Keyword(s):  
Natural Frequencies ◽  
Coupling Effect ◽  
Joint Stiffness ◽  
The Other ◽  
Dynamic Equations ◽  
Mode Shapes ◽  
Flexible Link ◽  
Flexible Joint ◽  
Special Cases ◽  
The Moment

The manipulator considered in this paper consists of a flexible link and a flexible joint. The coupling effect between link and joint deflections is investigated. The dynamic equations for the of manipulator are derived and analytical solutions are obtained. It is shown that the natural frequencies and mode shapes of a manipulator with both a flexible link and joint may be parametrized in terms of two ratios. One is the ratio of the moment of inertia of the link to that of the rotor and the other is the ratio of the link stiffness to the joint stiffness. Two special cases are discussed: (1) a manipulator with a relatively flexible link and a relatively rigid joint; and (2) a manipulator with a relatively flexible joint and a relatively rigid link.

scholarly journals The Study of Dynamic Modeling and Multivariable Feedback Control for Flexible Manipulators with Friction Effect and Terminal Load

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1522
Author(s):  
Fuli Zhang ◽  
Zhaohui Yuan
Keyword(s):  
Dynamic Model ◽  
Vibration Suppression ◽  
Control Method ◽  
Coupling Effect ◽  
Flexible Manipulator ◽  
Flexible Beam ◽  
Robot Dynamics ◽  
Joint Friction ◽  
Balance Principle ◽  
Multivariable Feedback

The flexible manipulato is widely used in the aerospace industry and various other special fields. Control accuracy is affected by the flexibility, joint friction, and terminal load. Therefore, this paper establishes a robot dynamics model under the coupling effect of flexibility, friction, and terminal load, and analyzes and studies its control. First of all, taking the structure of the central rigid body, the flexible beam, and load as the research object, the dynamic model of a flexible manipulator with terminal load is established by using the hypothesis mode and the Lagrange method. Based on the balance principle of the force and moment, the friction under the influence of flexibility and load is recalculated, and the dynamic model of the manipulator is further improved. Secondly, the coupled dynamic system is decomposed and the controller is designed by the multivariable feedback controller. Finally, using MATLAB as the simulation platform, the feasibility of dynamic simulation is verified through simulation comparison. The results show that the vibration amplitude can be reduced with the increase of friction coefficient. As the load increases, the vibration can increase further. The trajectory tracking and vibration suppression of the manipulator are effective under the control method of multi-feedback moment calculation. The research is of great significance to the control of flexible robots under the influence of multiple factors.

Vibration Control of a Flexible Link Manipulator Using an Array of Fiber-Optic Curvature Sensors and Piezoelectric Actuators

2007 ◽  
Author(s):  
Kerem Gurses ◽  
Bradley J. Buckman ◽  
Edward J. Park
Keyword(s):  
Motion Control ◽  
Sensor Array ◽  
Fiber Optic ◽  
Element Model ◽  
Flexible Manipulator ◽  
Flexible Link ◽  
Velocity Feedback ◽  
Lyapunov Approach ◽  
Single Link ◽  
Actuator Control

This paper presents a novel feedback sensing approach for actively suppressing vibrations of a single-link flexible manipulator. Slewing of the flexible link by a rotating hub induces vibrations in the link that persist long after the hub stops rotating. These vibrations are suppressed through a combined scheme of PD-based hub motion control and proposed piezoelectric (PZT) actuator control, which is a composite linear and velocity feedback controller. Lyapunov approach was used to synthesize the controller based on a finite element model of the system. Its realization was possible due to the availability of both linear and angular velocity feedback provided by a unique, commercially-available fiber optic curvature sensor array, called ShapeTape™. It is comprised of an array of fiber optic curvature sensors, laminated on a long, thin ribbon tape, geometrically arranged in such a way that, when it is embedded into the flexible link, the bend and twist of the link’s centerline can be measured. Experimental results show the effectiveness of the proposed approach.

On the Properties of a Dynamic Model of Flexible Robot Manipulators

1998 ◽  
Vol 120 (1) ◽  
pp. 8-14 ◽  
Author(s):  
Marco A. Arteaga
Keyword(s):  
Dynamic Model ◽  
Structural Properties ◽  
Robot Manipulators ◽  
Equations Of Motion ◽  
Mechanical Systems ◽  
Control Design ◽  
Flexible Manipulator ◽  
Robot Dynamics ◽  
Flexible Link ◽  
Flexible Robot

Control design of flexible robot manipulators can take advantage of the structural properties of the model used to describe the robot dynamics. Many of these properties are physical characteristics of mechanical systems whereas others arise from the method employed to model the flexible manipulator. In this paper, the modeling of flexible-link robot manipulators on the basis of the Lagrange’s equations of motion combined with the assumed modes method is briefly discussed. Several notable properties of the dynamic model are presented and their impact on control design is underlined.

An Approach for the Dynamics of Robotic Manipulators With Structural Flexibility of Links and Joints

1997 ◽  
Author(s):  
J. Kövecses ◽  
R. G. Fenton ◽  
W. L. Cleghorn
Keyword(s):  
Equations Of Motion ◽  
Robotic Manipulators ◽  
Structural Flexibility ◽  
Flexible Link ◽  
Dynamic Effects ◽  
Flexible Joint ◽  
Modeling And Analysis ◽  
Discrete Parameter ◽  
Rigid Link ◽  
Different Types

Abstract In this paper, an approach is presented for the dynamic modeling and analysis of robotic manipulators having structural flexibility in the links and joints. The formulation allows the user to include different types of flexibilities, as required. This approach includes the dynamic effects of joint driving systems by considering the mass and moments of inertia of their elements, the rotor-link interactions, and the gear reduction ratios; all of which can have significant influences on the behavior of the manipulator. Both distributed-discrete and discretized-discrete parameter models of a robot can be analysed. In the discretized-discrete case, dynamic equations of motion are developed for four model types: rigid link - rigid joint, rigid link - flexible joint, flexible link - rigid joint, and flexible link - flexible joint. An example of a two-link manipulator is considered. Simulation results are presented for different models (flexible joint - rigid link, rigid joint - flexible link, flexible joint - flexible link) of the manipulator. The computations show the influence of joint and link flexibilities on the manipulator performance.

Theoretical investigation into the modelling of a flexible beam with drive-line compliance

2002 ◽  
Vol 216 (8) ◽  
pp. 813-829 ◽  
Author(s):  
D J Purdy
Keyword(s):  
Theoretical Investigation ◽  
Transfer Functions ◽  
Flexible Beam ◽  
Direct Drive ◽  
Flexible Link ◽  
Line Model ◽  
Flexible Joint ◽  
Rigid Link ◽  
Dimensional Parameters ◽  
Weapons Systems

A comparison is made between the dynamics of three possible models for a flexible link and drive-line as used in some robotic or weapons systems. The three models considered are: model 1, a flexible link with compliance in the drive-line; model 2, flexible link with direct drive; and model 3, rigid link with drive-line compliance (flexible joint). Non-dimensional parameters are suggested for the models and comparisons are made between them, by examining the transfer functions poles (resonances) and zeros (anti-resonances). From the study, recommendations are made as to the suitability of the three models for different applications.

A study of the free vibration of flexible-link flexible-joint manipulators

2011 ◽  
Vol 225 (6) ◽  
pp. 1361-1371 ◽  
Author(s):  
M Vakil ◽  
R Fotouhi ◽  
P N Nikiforuk ◽  
F Heidari
Keyword(s):  
Joint Stiffness ◽  
Sensitivity Study ◽  
Frequency Equation ◽  
Mode Shapes ◽  
Flexible Link ◽  
Flexible Joint ◽  
Mass Moment ◽  
Mass Moment Of Inertia ◽  
Payload Mass ◽  
Analytical Expressions

In this article, explicit expressions for the frequency equation, mode shapes, and orthogonality of the mode shapes of a Single Flexible-link Flexible-joint manipulator (SFF) are presented. These explicit expressions are derived in terms of non-dimensional parameters which make them suitable for a sensitivity study; sensitivity study addresses the degree of dependence of the system’s characteristics to each of the parameters. The SFF carries a payload which has both mass and mass moment of inertia. Hence, the closed-form expressions incorporate the effect of payload mass and its mass moment of inertia, that is, the payload mass and its size. To check the accuracy of the derived analytical expressions, the results from these analytical expressions were compared with those obtained from the finite element method. These comparisons showed excellent agreement. By using the closed-form frequency equation presented in this article, a study on the changes in the natural frequencies due to the changes in the joint stiffness is performed. An upper limit for the joint stiffness of a SFF is established such that for the joint stiffness above this limit, the natural frequencies of a SFF are very close to those of its flexible-link rigid-joint counterpart. Therefore, the value of this limit can be used to distinguish a SFF from its flexible-link rigid-joint manipulator counterpart. The findings presented in this article enhance the accuracy and time-efficiency of the dynamic modeling of flexible-link flexible-joint manipulators. These findings also improve the performance of model-based controllers, as the more accurate the dynamic model, the better the performance of the model-based controllers.

Truncation errors of assumed shape modeling for flexible-link manipulators

2012 ◽  
Vol 226 (11) ◽  
pp. 2627-2644 ◽  
Author(s):  
Fatemeh Heidari ◽  
Mohammad Vakil ◽  
Reza Fotouhi ◽  
Peter N Nikiforuk
Keyword(s):  
Mode Shape ◽  
Dynamic Models ◽  
Transfer Functions ◽  
Degree Of Freedom ◽  
Flexible Manipulator ◽  
Mode Shapes ◽  
Physical Parameters ◽  
Flexible Link ◽  
Dimensional Parameters ◽  
Assumed Mode

The assumed mode shape method has been widely used to derive finite degree-of-freedom dynamic models for flexible-link manipulators, which theoretically have infinite degree-of-freedom dynamics. For a single flexible manipulator, this approximation changes locations of the zeros of transfer functions between base torque and end-effector displacement. The change in locations of zeros considerably affects accuracy of the model and therefore the performance of model-based controllers. This article presents a comprehensive study on the change in locations of zeros due to the truncation associated with assumed mode shape method. It is shown that the locations of approximate zeros depend on four non-dimensional parameters, whereas the locations of analytical zeros depend on only two non-dimensional parameters. Approximate zeros are obtained from assumed mode shape method models, whereas analytical zeros are derived from infinite order models. A thorough study of the differences between approximate zeros and analytical zeros versus the number of mode shapes as well as all the physical parameters is performed. Moreover, guidelines are provided to select the numbers of mode shapes such that the approximate zeros become close to the analytical zeros. These guidelines can easily be used by control and modeling engineers, making them valuable for modeling and control of flexible robot manipulators.

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