Reduction of Instrumented Linkage Data for Simple Anatomical Joint Models

1982 ◽  
Vol 104 (1) ◽  
pp. 218-226 ◽  
Author(s):  
G. L. Kinzel
Keyword(s):  
Optimization Theory ◽  
Degree Of Freedom ◽  
Linkage Data ◽  
Joint Models ◽  
Revolute Joint ◽  
Motion Data ◽  
Technical Personnel ◽  
Six Dof ◽  
Six Degree Of Freedom ◽  
Two Bodies

When measuring the total, six degree-of-freedom (dof) motion permitted by an anatomical joint, it is convenient to attach the ends of an instrumented linkage to the two bodies meeting at the joint and to measure six independent linkage variables as the bodies move. While this method gives a complete description of the motion, it does not permit the motion to be described in a quantifiable manner that non-technical personnel understand. It is therefore often desirable to model the joint as as simple joint which permits fewer than six dof’s, e.g., as a spherical or even a revolute joint. If this is done, a decision must be made as how the six-dof data will be used to define the motion data associated with these simple models. It is the purpose of this paper to present an approach for doing this based in part on optimization theory.

A Low-Cost Hexa Platform for Efficient Force Control Systems Using Industrial Manipulators

2009 ◽  
Vol 147-149 ◽  
pp. 1-6 ◽  
Author(s):  
Rafal Osypiuk ◽  
Torsten Kröger
Keyword(s):  
Control Systems ◽  
Force Control ◽  
Execution Time ◽  
Low Cost ◽  
Degree Of Freedom ◽  
Industrial Manipulators ◽  
Control Concept ◽  
Six Dof ◽  
Parallel Platform ◽  
Six Degree Of Freedom

This contribution presents a new force control concept for industrial six-degree of freedom (DOF) manipulators, which uses a Hexa platform that provides an active environmental stiffness for all six DOFs. The paper focuses on the Hexa platform and is split into two essential parts: (i) parallel platform construction, and (ii) application of force control with industrial manipulators using a six-DOF environmental stiffness. This mechatronic solution almost gives one hundred percent robustness for stiffness changes in the environment, what guaranties a significant shortening of execution time.

WRENCH-CLOSURE WORKSPACE OF SIX-DOF PARALLEL MECHANISMS DRIVEN BY 7 CABLES

2005 ◽  
Vol 29 (4) ◽  
pp. 541-552 ◽  
Author(s):  
Marc Gouttefarde ◽  
Clément M. Gosselin
Keyword(s):  
Cross Sections ◽  
Degree Of Freedom ◽  
Parallel Mechanisms ◽  
Six Dof ◽  
Moving Platform ◽  
Six Degree Of Freedom

The wrench-closure workspace (WCW) of six-degree-of-freedom (DOF) parallel cable-driven mechanisms is defined as the set of poses of the moving platform of the mechanism for which any external wrench can be balanced by tension forces in the cables. This workspace is fundamental in order to analyze and design parallel cable-driven mechanisms. This paper deals with the class of six-DOF mechanisms driven by seven cables. Two theorems, which provide efficient means to test whether a given pose of the moving platform belongs to the WCW, are proposed. One of these two theorems reveals the nature of the boundary of the constant-orientation cross sections of the WCW. Moreover, some of the possible applications of these theorems are discussed and illustrated.

scholarly journals A Six Degree of Freedom Epicyclic-Parallel Manipulator

2012 ◽  
Vol 4 (4) ◽  
Author(s):  
Chao Chen ◽  
Thibault Gayral ◽  
Stéphane Caro ◽  
Damien Chablat ◽  
Guillaume Moroz ◽  
...  
Keyword(s):  
Inverse Kinematics ◽  
Parallel Manipulator ◽  
Degree Of Freedom ◽  
Kinematics Analysis ◽  
End Effector ◽  
Six Dof ◽  
Six Degree Of Freedom

A new six-dof epicyclic-parallel manipulator with all actuators allocated on the ground is introduced. It is shown that the system has a considerably simple kinematics relationship, with the complete direct and inverse kinematics analysis provided. Further, the first and second links of each leg can be driven independently by two motors. The serial and parallel singularities of the system are determined, with an interesting feature of the system being that the parallel singularity is independent of the position of the end-effector. The workspace of the manipulator is also analyzed with future applications in haptics in mind.

Iterative feedback control based on frequency response model for a six-degree-of-freedom micro-vibration platform

2021 ◽  
pp. 107754632199731
Author(s):  
He Zhu ◽  
Shuai He ◽  
Zhenbang Xu ◽  
XiaoMing Wang ◽  
Chao Qin ◽  
...  
Keyword(s):  
Feedback Control ◽  
Frequency Response ◽  
Control Strategy ◽  
Degree Of Freedom ◽  
Small Displacement ◽  
Response Model ◽  
Parameter Uncertainties ◽  
Micro Vibration ◽  
Six Degree Of Freedom ◽  
Iterative Feedback

In this article, a six-degree-of-freedom (6-DOF) micro-vibration platform (6-MVP) based on the Gough–Stewart configuration is designed to reproduce the 6-DOF micro-vibration that occurs at the installation surfaces of sensitive space-based instruments such as large space optical loads and laser communications equipment. The platform’s dynamic model is simplified because of the small displacement characteristics of micro-vibrations. By considering the multifrequency line spectrum characteristics of micro-vibrations and the parameter uncertainties, an iterative feedback control strategy based on a frequency response model is designed, and the effectiveness of the proposed control strategy is verified by performing integrated simulations. Finally, micro-vibration experiments are performed with a 10 kg load on the platform. The results of these micro-vibration experiments show that after several iterations, the amplitude control errors are less than 3% and the phase control errors are less than 1°. The control strategy presented in this article offers the advantages of a simple algorithm and high precision and it can also be used to control other similar micro-vibration platforms.

scholarly journals Design and Calibration of a Hall Effect System for Measurement of Six-Degree-of-Freedom Motion within a Stacked Column

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3740
Author(s):  
Olafur Oddbjornsson ◽  
Panos Kloukinas ◽  
Tansu Gokce ◽  
Kate Bourne ◽  
Tony Horseman ◽  
...  
Keyword(s):  
Hall Effect ◽  
Degrees Of Freedom ◽  
Reactor Core ◽  
Degree Of Freedom ◽  
Life Extension ◽  
Scale Model ◽  
Design Development ◽  
Seismic Safety ◽  
Six Degrees Of Freedom ◽  
Six Degree Of Freedom

This paper presents the design, development and evaluation of a unique non-contact instrumentation system that can accurately measure the interface displacement between two rigid components in six degrees of freedom. The system was developed to allow measurement of the relative displacements between interfaces within a stacked column of brick-like components, with an accuracy of 0.05 mm and 0.1 degrees. The columns comprised up to 14 components, with each component being a scale model of a graphite brick within an Advanced Gas-cooled Reactor core. A set of 585 of these columns makes up the Multi Layer Array, which was designed to investigate the response of the reactor core to seismic inputs, with excitation levels up to 1 g from 0 to 100 Hz. The nature of the application required a compact and robust design capable of accurately recording fully coupled motion in all six degrees of freedom during dynamic testing. The novel design implemented 12 Hall effect sensors with a calibration procedure based on system identification techniques. The measurement uncertainty was ±0.050 mm for displacement and ±0.052 degrees for rotation, and the system can tolerate loss of data from two sensors with the uncertainly increasing to only 0.061 mm in translation and 0.088 degrees in rotation. The system has been deployed in a research programme that has enabled EDF to present seismic safety cases to the Office for Nuclear Regulation, resulting in life extension approvals for several reactors. The measurement system developed could be readily applied to other situations where the imposed level of stress at the interface causes negligible material strain, and accurate non-contact six-degree-of-freedom interface measurement is required.

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