On the Computation of Degrees-of-Freedom: A Didactic Perspective

2005 ◽  
Author(s):  
E. Pennestri` ◽  
M. Cavacece ◽  
L. Vita
Keyword(s):  
Degrees Of Freedom ◽  
Analytical Approach ◽  
Kinematic Structure ◽  
Unilateral Constraints ◽  
Didactic Issues

Some didactic issues associated with the computation of degrees-of-freedom (d.o.f.) are herein discussed. In particular the paper reports different definitions and methodologies of computation of this important parameter. It is also proposed an analytical approach to the d.o.f. computation of planar figures subjected to unilateral constraints. Mechanisms with variable kinematic structure are included in the present analysis. Some ambiguities in the d.o.f. definition are pointed out.

scholarly journals The Impact of the Support System’s Kinematic Structure on Selected Kinematic and Dynamic Quantities of an Experimental Crane

2014 ◽  
Vol 8 (4) ◽  
pp. 189-193 ◽  
Author(s):  
Arkadiusz Trąbka
Keyword(s):  
Comparative Analysis ◽  
Computational Model ◽  
Experimental Model ◽  
Support System ◽  
Degrees Of Freedom ◽  
Kinematic Structure ◽  
Unilateral Constraints ◽  
Adams Software ◽  
The Impact

Abstract This paper presents a comparative analysis of two kinematic structures of the support system (with supports with bilateral and unilateral constraints), which were used in an experimental model of a crane. The computational model was developed by using the ADAMS software. The impact of the kinematic structure of the support system on selected kinematic and dynamic values that were recorded during the slewing motion was analysed. It was found, among other things, that an increased number of degrees of freedom of the support system leads to multiple distortions of time characteristics of kinematic and dynamic quantities.

Dynamic Modeling of a Parallel Manipulator With Three Translational Degrees of Freedom

1998 ◽  
Author(s):  
Richard Stamper ◽  
Lung-Wen Tsai
Keyword(s):  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Close Agreement ◽  
Jacobian Matrix ◽  
Parallel Manipulators ◽  
Kinematic Structure ◽  
End Effector ◽  
Moving Platform ◽  
Euler Approach ◽  
Computationally Intensive

Abstract The dynamics of a parallel manipulator with three translational degrees of freedom are considered. Two models are developed to characterize the dynamics of the manipulator. The first is a traditional Lagrangian based model, and is presented to provide a basis of comparison for the second approach. The second model is based on a simplified Newton-Euler formulation. This method takes advantage of the kinematic structure of this type of parallel manipulator that allows the actuators to be mounted directly on the base. Accordingly, the dynamics of the manipulator is dominated by the mass of the moving platform, end-effector, and payload rather than the mass of the actuators. This paper suggests a new method to approach the dynamics of parallel manipulators that takes advantage of this characteristic. Using this method the forces that define the motion of moving platform are mapped to the actuators using the Jacobian matrix, allowing a simplified Newton-Euler approach to be applied. This second method offers the advantage of characterizing the dynamics of the manipulator nearly as well as the Lagrangian approach while being less computationally intensive. A numerical example is presented to illustrate the close agreement between the two models.

Reconfiguration of Kinematic Structure for Changing Motion Requirement Based on Reusability Evaluation in Lie Algebra

2002 ◽  
Author(s):  
Hitoshi Tokunaga ◽  
Norio Matsuki ◽  
Satoshi Imamura ◽  
Fumiki Tanaka ◽  
Takeshi Kishinami
Keyword(s):  
Lie Algebra ◽  
Degrees Of Freedom ◽  
Manufacturing System ◽  
New Method ◽  
Kinematic Structure ◽  
Kinematic Design ◽  
Structure And Motion ◽  
Inclusion Relations ◽  
Requirement Change

This paper presents a new method for adapting the existing manufacturing system for a requirement change, such as the change of a required motion task, by modifying its kinematic structure from the viewpoint of the degrees of freedom of the end effecter of the mechanism. In a previous report, the authors formulated the kinematic structure and motion task using Lie algebra. In this report, using these representations and their inclusion relations, the authors propose a method for evaluating the reusability of a kinematic structure for a newly specified motion task, and then propose a method for reconfiguring the mechanism in Lie algebra according to the result of the reusability evaluation. Finally, in order to evaluate the usefulness of the proposed method, it is applied to a kinematic design example of a mechanism.

Topology Analyses and Position Solution Based on Asymmetric and Fewer DOF Parallel Robots

2011 ◽  
Vol 308-310 ◽  
pp. 1252-1257
Author(s):  
Ping An Liu ◽  
Xiao Heng Shi
Keyword(s):  
Degrees Of Freedom ◽  
Analytical Approach ◽  
Structure Design ◽  
Parallel Robots ◽  
Forward Kinematics ◽  
Topology Structure ◽  
Constrained Equations ◽  
Position Solution

By using the theory and method of topology structure design of parallel robotic mechanisms, the degrees of freedom (DOF) is analyzed based on 4-DOF(3T1R) asymmetric parallel robots in this paper. Then, the inverse and forward kinematics of the manipulator are calculated through establishment of constrained equations with analytical approach.

Design of a master device for controlling multi-moduled continuum robots

2015 ◽  
Vol 231 (10) ◽  
pp. 1921-1931 ◽  
Author(s):  
Hyun-Soo Yoon ◽  
Byung-Ju Yi
Keyword(s):  
Degrees Of Freedom ◽  
Control Experiment ◽  
Light Weight ◽  
Kinematic Structure ◽  
Continuum Robots ◽  
Two Degrees Of Freedom ◽  
Forward Kinematic ◽  
Master Device ◽  
Kinematic Solution

Few interface systems designed to control continuum robots have been developed. This work presents a master device for multi-unit continuum robots. The master mechanism has the same kinematic structure as the slave device. The kinematic structure, which uses a spring as a backbone, allows for a unique forward kinematic solution. This design is slim-sized, light-weight, and easy to implement. As an example mechanism, a continuum unit with two degrees of freedom was developed. Two-unit modules were assembled to generate four degrees of freedom. The performance of the master device is verified through a master-slave control experiment.

Complete Atlas Database of 2-DOF Kinematic Chains and Creative Design of Mechanisms

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Huafeng Ding ◽  
Wenao Cao ◽  
Andrés Kecskeméthy ◽  
Zhen Huang
Keyword(s):  
Creative Process ◽  
Degrees Of Freedom ◽  
Systematic Approach ◽  
Computer Models ◽  
Creative Design ◽  
Kinematic Structure ◽  
Topological Graphs ◽  
Kinematic Chains ◽  
First Time ◽  
Intuitive Manner

The creation of novel kinematic structures of mechanisms still represents a major challenge in the quest for developing new, innovative devices. In this setting, computer models that can automatically generate and visualize all possible independent structures in an intuitive manner prove to be valuable as a support in the creative process of the designer. This paper proposes an automatic approach for establishing the complete atlas database of 2-DOF kinematic chains and a systematic approach for the creative design of mechanisms based on such an atlas. First, the transformation of the kinematic structure into a graph-based representation is addressed. Then, an approach for the generation of all nonfractionated topological graphs of 2-DOF (degrees of freedom) kinematic chains using contracted graphs as well as a method for synthesizing all the fractionated topological graphs through the combination of corresponding 1-DOF kinematic chains are addressed. Based on these methods, the complete atlas database of 2-DOF kinematic chains up to 15 links is established in this paper for the first time. Using this complete database, a systematic approach for the creative design of mechanisms can be derived, as illustrated for the example of an 11-link 2-DOF rode tractor.

Automatic Analysis of Kinematic Structure of Planetary Gear Trains

1993 ◽  
Vol 115 (3) ◽  
pp. 631-638 ◽  
Author(s):  
Cheng-Ho Hsu ◽  
Kin-Tak Lam
Keyword(s):  
Computer Program ◽  
Degrees Of Freedom ◽  
Planetary Gear ◽  
Automatic Analysis ◽  
Kinematic Structure ◽  
Identification Number ◽  
Interactive Computer Program ◽  
Planetary Gear Trains ◽  
Gear Trains

This paper presents a systematic algorithm for the automatic analysis of the kinematic structure of planetary gear trains with any number of degrees of freedom. The canonical displacement graphs and rotation graphs are introduced to represent the kinematic structure of planetary gear trains. Next, a single identification number method is presented to identify the displacement isomorphism of planetary gear trains. Then, nonfractionated multi-DOF planetary gear trains can be identified from their rotation graphs. Finally, an interactive computer program is developed for the automatic analysis of the kinematic structure of planetary gear trains. The result of this work is beneficial to the development of the new planetary gear trains.

Kinematic Structure and Functional Analysis of Shaft Couplings Involving Pode Joints

1983 ◽  
Vol 105 (4) ◽  
pp. 672-680 ◽  
Author(s):  
E. Akbil ◽  
T. W. Lee
Keyword(s):  
Functional Analysis ◽  
Degrees Of Freedom ◽  
Systematic Approach ◽  
Degree Of Freedom ◽  
Graph Representation ◽  
Kinematic Structure ◽  
Mobility Analysis ◽  
New Approaches ◽  
New Concepts ◽  
Basic Concepts

This paper introduces some basic concepts and new approaches regarding the kinematic structure and functional analysis of mechanisms. The theory and approach are illustrated on shaft couplings involving pode joints. Kinematic structure of pode joints is given and some new concepts, such as multiple contacting points and effective and idle degrees-of-freedom, are introduced. A systematic approach which includes a modified graph representation and a modified degree-of-freedom equation is presented. Using this approach the mobility analysis of a class of difficult and complex mechanisms can be treated. Several specific examples are presented to illustrate the basic theory.

scholarly journals Finding Optimal Manipulator Arm Shapes to Avoid Collisions in a Static Environment

2020 ◽  
Vol 11 (1) ◽  
pp. 64
Author(s):  
Tomáš Kot ◽  
Zdenko Bobovský ◽  
Mathias Brandstötter ◽  
Václav Krys ◽  
Ivan Virgala ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Particle Swarm Optimization Algorithm ◽  
Industrial Robots ◽  
Kinematic Structure ◽  
Typical Structure ◽  
Swarm Optimization ◽  
Six Degrees Of Freedom ◽  
Manipulator Arm ◽  
The Given ◽  
Collaborative Robot

In situations of a confined workplace with a lot of obstacles and a complicated required trajectory of the endpoint of an industrial or collaborative robot, it may be impossible to find a suitable robot and its position within the workplace to fulfill the given task. In some cases, it could be favorable to design a custom manipulator arm with an unusual kinematic structure or shapes of some of its links. This article presents a novel way of finding the optimal lengths and shapes of two crucial links of a manipulator arm, where the target lengths are as short as possible to reduce mass, and the shape in the form of a Bézier curve is chosen to avoid collisions. The chosen type of kinematic structure of the manipulator arm is fixed and is based on the most typical structure of existing industrial robots, with six degrees of freedom. Two algorithm variants were proposed; one method uses iterations to find the solution based on in-depth collision analysis, and the second method uses the particle swarm optimization algorithm. Both methods were implemented in a simulation system and verified in several testing workplaces.

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