A Study of an Arm Type Damper Consisting of Two Links, Two Joints and a Hinge

2002 ◽  
Author(s):  
Taichi Matsuoka ◽  
Kenichiro Omata ◽  
Yasuhisa Okano
Keyword(s):  
Degrees Of Freedom ◽  
Vibration Suppression ◽  
Experimental Results ◽  
Shaking Table ◽  
Friction Damper ◽  
Six Degrees Of Freedom ◽  
Human Arm ◽  
Three Degree Of Freedom ◽  
Ball Joints ◽  
Theoretical Results

In this paper, an arm type passive damper consisting of two links, two joints and a hinge, which is similar to a human arm, has developed. Two magnetic ball joints were used for the joints and a rotary friction damper was used for the hinge. The arm type damper has six degrees of freedom and gives damping in three translational and three rotational directions. The resisting force characteristics of the damper in three translational directions were analyzed. A trial damper was made and the load-displacement curves of the damper in three translational directions were measured. The experimental results agree with the theoretical results to some degree. Next, the damper was attached to a three-degree-of-freedom system composed of a mass, three guide rails and four coil springs, in which the mass is able to move in three translational directions along the guide rails. The seismic responses of the mass in three translational directions were measured using a two-dimensional electrohydraulic type shaking table and the experimental results were compared with the calculated results obtained by the Mathematica 3.0. The experimental results agree with the calculated results to some degree, and the effects of vibration suppression of the damper and the propriety of the calculations were substantiated.

Development of Position-Orientation Decoupled Spatial In-Parallel Actuated Mechanisms with Six Degrees of Freedom

2005 ◽  
Vol 17 (1) ◽  
pp. 59-68 ◽  
Author(s):  
Yukio Takeda ◽  
◽  
Kouji Kamiyama ◽  
Yoshihisa Maki ◽  
Masaru Higuchi ◽  
...  
Keyword(s):  
Kinematic Analysis ◽  
Degrees Of Freedom ◽  
Experimental Results ◽  
Six Degrees Of Freedom ◽  
Position And Orientation ◽  
Basic Equations ◽  
Number Synthesis ◽  
Theoretical Results

We propose a new structure for spatial in-parallel actuated mechanisms with six degrees of freedom in which the output link’s position and orientation are decoupled. Number synthesis of the position submechanism, a partial mechanism for the position-orientation decoupled mechanism, was conducted, and fifteen mechanisms were clarified. Basic equations for kinematic analysis were derived for four of the obtained mechanisms, and procedures to analyze their forward/inverse displacement were investigated. Their workspaces and swing angles were numerically evaluated based on these equations. Experimental results using an experimental position-orientation decoupled mechanism were presented to support these theoretical results.

scholarly journals Modelling of a Microslip Friction Damper Subjected to Translation and Rotation

1999 ◽  
Author(s):  
Gabor Csaba
Keyword(s):  
Surface Roughness ◽  
Degrees Of Freedom ◽  
Forced Response ◽  
Least Square ◽  
Contact Model ◽  
Contact Radius ◽  
Algebraic Equations ◽  
Friction Damper ◽  
Six Degrees Of Freedom ◽  
Winkler Elastic Foundation

This paper presents a friction interface model where one of the mating surfaces is curved. The model is based on a discretization of the Winkler elastic foundation model and is general in the sense that it allows for relative motion in all six degrees of freedom. The variables for the contact model are based on damper geometry and material data, except coefficient of friction and tangential stiffness coefficient, which have to be measured. Simulated and experimental hysteresis curves are presented. A model of a curved wedge damper has been developed using the contact model. An algorithm for solving forces and displacement when the damper is allowed to move in all six degrees of freedom has been presented. The governing algebraic equations are solved using a nonlinear least-square method routine in a commercial software package. Forced response of a beam-damper-beam test set-up has been simulated and compared with experiments. The results highlighted some effects which have not been modelled e.g. the actual contact area between damper and blade is influenced by surface roughness for low normal loads. It is assumed that this effect resulted in problems in getting agreement between experiments and analysis. The influence of surface roughness is assumed to be negligible when vibrations of real turbomachinery are considered. This is due to the fact that both normal and excitation force on the clamper are about ten times higher than what was used in the experiments and simulations in this paper. Variation of contact radius of the damper shows that a larger radius e.g. a flatter contact gives better damping and increases the resonance frequency. The disadvantage is that the alignment of the damper becomes more unreliable.

scholarly journals Design and Development of a Littoral AUV for Underwater Target Localization and Homing Using Vision and SONAR Module

ISRN Robotics ◽  
2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
R. K. Sinha ◽  
Aayush Jha ◽  
Faheem Ahmad ◽  
Vivek Mishra ◽  
Prateek Murgai ◽  
...  
Keyword(s):  
Power Systems ◽  
Degrees Of Freedom ◽  
Autonomous Underwater Vehicle ◽  
Mechanical Design ◽  
Water Environment ◽  
Experimental Results ◽  
Design And Development ◽  
Sound Sources ◽  
Six Degrees Of Freedom ◽  
Underwater Target

This paper presents the design and development of a modular littoral autonomous underwater vehicle called “ZYRA” having six degrees of freedom for performing the following tasks underwater: target (sound sources emitting frequencies between 1 Hz and 180 KHz) localization and homing, buoy detection. The development of the AUV has been divided into, namely, five sections: mechanical design and fabrication, embedded and power systems, control and software, image processing, and underwater acoustics. A fully functional AUV has been tested in a self-created arena with different tasks spread out in a shallow water environment. Two different kinds of experimental results have been presented: first the experimental results of the SONAR module and second based on the number of successful outcomes per total number of trials for each task.

Substructured Dynamic Testing of Substation Disconnect Switches

2016 ◽  
Vol 32 (1) ◽  
pp. 567-589 ◽  
Author(s):  
Mohamed A. Moustafa ◽  
Khalid M. Mosalam
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Testing ◽  
Flexible Structures ◽  
Shaking Table ◽  
Support Structure ◽  
Six Degrees Of Freedom ◽  
Out Of Plane ◽  
Qualification Testing ◽  
Substation Equipment ◽  
Electrical Substation

The paper demonstrates the substructuring concept in seismic qualification testing of 550 kV electrical substation disconnect switches. In this study, the full and substructured (i.e., without support structure) switches are tested on a six degrees of freedom (DOFs) shaking table. Different combinations of translational and rotational excitations are obtained from full switch tests and used in the substructured ones. The behavior of the post insulators of the switches are compared to demonstrate validity and identify limitations of the substructuring concept applied to electrical substation equipment. From this comparison, critical DOFs for the response of post insulators in switches supported on flexible structures are identified. It is concluded that the in-plane and out-of-plane behavior of the investigated post insulators are uncoupled. The substructured tests driven by combined translational and rotational signals showed the best match with the full switch tests because the out-of-plane rotations contribute significantly to the response of the post insulators.

scholarly journals The Ariadne's Clew Algorithm

1998 ◽  
Vol 9 ◽  
pp. 295-316 ◽  
Author(s):  
E. Mazer ◽  
J. M. Ahuactzin ◽  
P. Bessiere
Keyword(s):  
Path Planning ◽  
Degrees Of Freedom ◽  
Optimization Problems ◽  
Dynamic Environment ◽  
Dynamic Environments ◽  
Experimental Results ◽  
High Dimensional ◽  
New Approach ◽  
Six Degrees Of Freedom ◽  
Moving Obstacle

We present a new approach to path planning, called the ``Ariadne's clew algorithm''. It is designed to find paths in high-dimensional continuous spaces and applies to robots with many degrees of freedom in static, as well as dynamic environments --- ones where obstacles may move. The Ariadne's clew algorithm comprises two sub-algorithms, called SEARCH and EXPLORE, applied in an interleaved manner. EXPLORE builds a representation of the accessible space while SEARCH looks for the target. Both are posed as optimization problems. We describe a real implementation of the algorithm to plan paths for a six degrees of freedom arm in a dynamic environment where another six degrees of freedom arm is used as a moving obstacle. Experimental results show that a path is found in about one second without any pre-processing.

Alternative Control Design Approach to Shaking Facilities for Re-Creating Seismic Motion

2002 ◽  
Author(s):  
Eiji Sato ◽  
Tomoyoshi Kakegawa ◽  
Taku Suzuki ◽  
Koichi Kajiwara ◽  
Yasutaka Tagawa ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Control Method ◽  
Control Design ◽  
Maximum Load ◽  
Shaking Table ◽  
Three Dimensions ◽  
Test Model ◽  
Test Models ◽  
Under Construction ◽  
Three Degree Of Freedom

The 3-D Full-Scale Earthquake Testing Facility (E-Defense) is now under construction in Miki City near Kobe. When completed, the facility will have a 750-ton shaking table measuring 20m by 15m, with a maximum load mass of 1200 tons. It will be able to create vibration in three dimensions with six degrees of freedom. However, the test model considered for this facility has a mass of 1200 tons compared to the shaking table mass of 750 tons, i.e., 1.6 times as heavy as the shaking table and much larger than ordinary test models. In addition, the vibration characteristics change considerably during the experiment due to the damage done to the test weight. Therefore, a better control design is urgently needed in order to overcome these problems. This research suggests a control method that will reproduce the earthquake wave accurately on the shaking table and will consider the robustness. Moreover, we will verify its efficiency by performing a control experiment using an existing two–dimensional, three-degree-of-freedom small shaking table, to which this control method is applied.

Analysis of Three Degree of Freedom 6×6 Tensegrity Platform

2006 ◽  
Author(s):  
Antoin Baker ◽  
Carl D. Crane
Keyword(s):  
Degrees Of Freedom ◽  
Rigid Bodies ◽  
Degree Of Freedom ◽  
Parallel Mechanisms ◽  
Constant Length ◽  
Six Degrees Of Freedom ◽  
Tensegrity Structure ◽  
Tension And Compression ◽  
Three Degree Of Freedom ◽  
Primary Contribution

The mechanism studied in this paper is a three degree of freedom 6×6 tensegrity structure. A tensegrity structure is one that balances internal (pre-stressed) forces of tension and compression. These structures have the unique property of stabilizing themselves if subjected to certain types of disturbances. The structure analyzed in this paper consists of two rigid bodies (platforms) connected by a total of six members. Three of the members are noncompliant constant-length struts and the other three members consist of springs. For typical parallel mechanisms, if the bottom platform is connected to the ground and the top platform is connected to the base by six compliant leg connectors, the top platform will have six degrees of freedom relative to the bottom platform. However, because three of the six members connecting the two platforms are noncompliant constant-length struts, the top platform has only three degrees of freedom. The primary contribution of this paper is the analysis of the three degree of freedom tensegrity platform. Specifically, given the location of the connector points on the base and top platforms, the lengths of the three noncompliant constant-length struts, and the desired location of a point embedded in the top platform measured with respect to a coordinate system attached to the base, all possible orientations of the top platform are determined.

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