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.

Dynamic Modeling and Analysis of Astronauts’ Exercise during Spaceflight

2012 ◽  
Vol 569 ◽  
pp. 576-584
Author(s):  
Hao Chen ◽  
Dong Xu Li
Keyword(s):  
Control System ◽  
Topological Structure ◽  
Equations Of Motion ◽  
Low Frequency ◽  
Cycle Ergometer ◽  
Microgravity Environment ◽  
Dynamic Effects ◽  
Dynamic Coupling ◽  
Modeling And Analysis ◽  
Simulation Results

Astronauts’ exercise during spaceflight will bring low-frequency disturbance to the spacecraft. In order to analyze the corresponding dynamic effects on the spacecraft, an astronaut-cycle ergometer-spacecraft system is taken as an example. The dynamic model is established in this paper. The topological structure of the astronaut-cycle ergometer-spacecraft system is given and equalized to an open tree system. Utilizing recursive relation of displacement and velocity between connected units, equations of motion of the system are reduced to the spacecraft. Simulation implies astronauts’ exercise will result in rotational drift of the spacecraft. Meanwhile, the microgravity environment is heavily destroyed. Compare with traditional modeling method, our method is more accurate as it considers dynamic coupling effects. The simulation results can be considered as a reference to the control system and it also reveal changes of microgravity environment.

Dynamic Modeling and Analysis of Space Manipulator Considering the Flexible of Joint and Link

2013 ◽  
Vol 823 ◽  
pp. 270-275 ◽  
Author(s):  
Pan Dong ◽  
Zhao Yang ◽  
Zhang Yue ◽  
Wei Cheng ◽  
E Wei
Keyword(s):  
Joint Stiffness ◽  
Low Frequency ◽  
Flexible Link ◽  
Large Space ◽  
Flexible Joint ◽  
Modeling And Analysis ◽  
Position Accuracy ◽  
Low Frequency Vibration ◽  
Space Manipulators ◽  
The Impact

The long length, light weight, low frequency, flexible joint and link of large space manipulators impact dynamic stability and position accuracy seriously. In this paper, dynamical model of space flexible manipulators system is build base on Lagrange method. With three DOF manipulators as the research object, the impact of flexible link, joint stiffness and clearance on the system frequency and end position accuracy of manipulator is simulated and analyzed. The results indicate that the flexible joint lead to low frequency vibration and flexible link lead to high frequency vibration. Low frequency vibration is the dominant impact of end position accuracy, Flexible joint have greater impact on the dynamic characteristics of system than that of flexible link.

The Kinematics of Robotic Manipulators With Flexible Links Using an Equivalent Rigid Link System (ERLS) Model

1991 ◽  
Vol 113 (1) ◽  
pp. 48-53 ◽  
Author(s):  
Liang-Wey Chang ◽  
J. F. Hamilton
Keyword(s):  
Inverse Kinematics ◽  
Robotic Manipulators ◽  
Rigid Body Dynamics ◽  
Global Motion ◽  
Flexible Link ◽  
Small Motion ◽  
Flexible Links ◽  
Rigid Link ◽  
Body Dynamics ◽  
Large Motion

The Equivalent Rigid Link System (ERLS) is presented for the analysis of the kinematics of manipulators with flexible links. The concept of the ERLS is to separate the rigid-body dynamics and structural dynamics. The global motion of the flexible-link system is thereby separated into a large motion with a superimposed small motion. The large motion is represented by the ERLS and the small motion is due to the deviations with respect to the ERLS. The complete motion of manipulators is described by homogeneous transformations. The Jacobian and inverse kinematics are also presented in this paper.

scholarly journals Stiffness Modeling of Robotic-Manipulators Under Auxiliary Loadings

2012 ◽  
Author(s):  
Alexandr Klimchik ◽  
Anatol Pashkevich ◽  
Stéphane Caro ◽  
Damien Chablat
Keyword(s):  
Robotic Manipulators ◽  
Computationally Efficient ◽  
End Effector ◽  
Efficient Procedure ◽  
Stiffness Modeling ◽  
Cartesian Stiffness Matrix ◽  
Different Types ◽  
Mapping Equation ◽  
Linear Force ◽  
Cartesian Stiffness

The paper focuses on the extension of the virtual-joint-based stiffness modeling technique for the case of different types of loadings applied both to the robot end-effector and to manipulator intermediate points (auxiliary loading). It is assumed that the manipulator can be presented as a set of compliant links separated by passive or active joints. It proposes a computationally efficient procedure that is able to obtain a non-linear force-deflection relation taking into account the internal and external loadings. It also produces the Cartesian stiffness matrix. This allows to extend the classical stiffness mapping equation for the case of manipulators with auxiliary loading. The results are illustrated by numerical examples.

On flexible link manipulators: modeling and analysis using the algebra of rotations

Robotica ◽  
1994 ◽  
Vol 12 (4) ◽  
pp. 371-382 ◽  
Author(s):  
F. Xi ◽  
R.G. Fenton
Keyword(s):  
Nonlinear Coupling ◽  
Flexible Link ◽  
Complete Model ◽  
Modeling And Analysis ◽  
Displacement Equation

SUMMARYIn this paper, a complete model of the elasto-kinematics is formulated in terms of a new kinematic notation, called the algebra of rotations. Based on this formulation, the elegant and concise expressions are derived for the displacement equation and especially the Jacobians governing the motion mapping between the manipulator tip and joint variables as well as link deflections. Introduction of the elasto-kinematics into the elasto-dynamics can directly take into consideration the nonlinear coupling between joint variables and link deflections, and thus improve the result of the elasto-dynamics.

Minimizing the Strain Energy for Flexible-Link Cooperating Manipulators

1996 ◽  
Author(s):  
Qiao Sun ◽  
Inna Sharf ◽  
Meyer Nahon
Keyword(s):  
Strain Energy ◽  
Minimum Energy ◽  
Force Distribution ◽  
Structural Flexibility ◽  
Flexible Link ◽  
Minimum Energy Consumption ◽  
Optimal Load ◽  
Cooperating Manipulators ◽  
Minimum Potential ◽  
Potential Damage

Abstract In control of cooperating manipulator systems, force distribution is a central problem. For rigid manipulators, solutions are based on various criteria such as minimum potential damage to the grasped object, minimum energy consumption and optimal load distribution in actuators. However, when considering manipulators with structural flexibility, minimizing the deflections of the mechanical components becomes a highly desirable objective. In this paper, we propose a force distribution scheme based on a local minimum of the strain energy stored in the elastic links of the cooperating manipulators. Numerical example are given to demonstrate the effectiveness of the scheme.

scholarly journals Differential Diffusivity Effects in Reactive Convective Dissolution

Fluids ◽  
2018 ◽  
Vol 3 (4) ◽  
pp. 83 ◽  
Author(s):  
V. Loodts ◽  
H. Saghou ◽  
B. Knaepen ◽  
L. Rongy ◽  
A. De Wit
Keyword(s):  
Diffusion Coefficients ◽  
Reaction Rate ◽  
Chemical Species ◽  
Mixing Zone ◽  
Simultaneous Presence ◽  
Dynamic Effects ◽  
Density Profiles ◽  
Differential Diffusion ◽  
Different Types ◽  
Double Diffusive

When a solute A dissolves into a host fluid containing a reactant B, an A + B → C reaction can influence the convection developing because of unstable density gradients in the gravity field. When A increases density and all three chemical species A, B and C diffuse at the same rate, the reactive case can lead to two different types of density profiles, i.e., a monotonically decreasing one from the interface to the bulk and a non-monotonic profile with a minimum. We study numerically here the nonlinear reactive convective dissolution dynamics in the more general case where the three solutes can diffuse at different rates. We show that differential diffusion can add new dynamic effects like the simultaneous presence of two different convection zones in the host phase when a non-monotonic profile with both a minimum and a maximum develops. Double diffusive instabilities can moreover affect the morphology of the convective fingers. Analysis of the mixing zone, the reaction rate, the total amount of stored A and the dissolution flux further shows that varying the diffusion coefficients of the various species has a quantitative effect on convection.

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