scholarly journals CONTROL OF THE SIX DEGREES OF FREEDOM OF A FLOATING BODY USING VIDEO IMAGING TECHNIQUES: MONITORING THE OPERATION OF FLOATING GATE OPENING AND CLOSING AT CAMPAMENTO'S DRY DOCK (ALGECIRAS BAY)

2012 ◽  
Vol 1 (33) ◽  
pp. 33
Author(s):  
Rafael Molina Sánchez ◽  
Miguel Ángel Cabrerizo Morales ◽  
Francisco De los Santos Ramos ◽  
Alberto Camarero Orive ◽  
Clara Matutano Molina
Keyword(s):  
Degrees Of Freedom ◽  
Imaging Techniques ◽  
Rigid Bodies ◽  
Floating Gate ◽  
Floating Body ◽  
Video Imaging ◽  
Floating Structures ◽  
Six Degrees Of Freedom ◽  
Implementation Costs ◽  
Dry Dock

The activity of floating structures within the harbours is influenced by physical and exploitation agents. Therefore, the study of operational thresholds overcoming is crucial to limit the risk in port operations. In order to achieve this objective it is necessary, a deep knowledge of use, exploitation and environmental agents, as well as the response of the system. To study the response of such systems it is necessary to measure, besides the forces that coerce the free float, the displacements, rotations and accelerations in all six degrees of freedom of rigid bodies. With this aim up to now, gyroscopes (Stahl et al.1983 B.), accelerometers (LJWeyers et al. 1985), load cells, RTK-GPS systems infrared (Johanning et al.2007), laser, etc., have been used to carry out the monitoring of floating elements, on both model and prototype. However, these instrumental techniques are associated with large investments, setting up and calibration procedures, and equipment maintenance. Since 2008, the Laboratory of Ports at UPM ( Chair Pablo Bueno), is developing new instrumental techniques, for field and laboratory application, in the framework of following two strategic lines, part of the agreement reached with the Public Entity Puertos del Estado: "Development of non-intrusive instrumentation oriented monitoring of port infrastructure" and "Study of reliability in the areas of design, optimization and exploitation of maritime infrastructure". The use of video imaging techniques offers advantages, such as low maintenance, non intrusive and low implementation costs. Therefore, this paper aims to explore the practical application of video imaging techniques for monitoring floating structures, as a tool to support harbour operations. Precisely in this work we develop a monitoring example of the floating gate of Campamento’s dry dock, in Algeciras’ Bay.

Theory and Method of Dynamic Modeling for Multilayer Vibration Isolation System

2000 ◽  
Author(s):  
Liao Dao-Xun ◽  
Lu Yong-Zhong ◽  
Huang Xiao-Cheng
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Vibration Isolation ◽  
Rigid Bodies ◽  
Design Calculation ◽  
Isolation System ◽  
Dry Land ◽  
Vibration Isolation System ◽  
Six Degrees Of Freedom ◽  
Floating Raft

Abstract The multilayer vibration isolation system has been widely applied to isolate vibration in dynamic devices of ships, high-speed vehicles forging hammer and precise instruments. The paper is based on the coordinate transformation of space general motion for mass blocks (rigid bodies) and Lagrangian equation of multilayer vibration isolation system. It gives a strict mathematical derivation on the differential equation of the motion for the system with six degrees of freedom of relative motion between mass blocks (including base). The equations are different from the same kind of equations in the reference literatures. It can be used in the floating raft of ships in order to isolates vibration and decrease noise, also used in design calculation of the multilayer vibration isolation for dynamic machines and precise instruments on the dry land.

Validation of a Novel 3D-Printed Instrumented Spatial Linkage That Measures Changes in the Rotational Axes of the Tibiofemoral Joint

2013 ◽  
Author(s):  
Daniel P. Bonny ◽  
S. M. Howell ◽  
M. L. Hull
Keyword(s):  
Degrees Of Freedom ◽  
Rigid Bodies ◽  
Anatomic Landmarks ◽  
Tibiofemoral Joint ◽  
Six Degrees Of Freedom ◽  
Revolute Joints ◽  
Flexion Extension ◽  
3D Printed ◽  
Total Knee ◽  
Position And Orientation

The two kinematic axes of the tibiofemoral joint, the flexion-extension (F-E) and longitudinal rotation (LR) axes [1], are unrelated to the anatomic landmarks often used to align prostheses during total knee arthroplasty (TKA) [1, 2]. As a result, conventional TKA changes the position and orientation of the joint line, thus changing the position and orientation of the F-E and LR axes and consequently the kinematics of the knee. However, the extent to which TKA changes these axes is unknown. An instrument that can measure the locations of and any changes to these axes is an instrumented spatial linkage (ISL), a series of six instrumented revolute joints that can measure the six degrees of freedom of motion (DOF) between two rigid bodies without constraining motion. Previously, we computationally determined how best to design and use an ISL such that rotational and translational errors in locating the F-E and LR axes were minimized [3]. However, this ISL was not constructed and therefore its ability to measure changes in the axes has not been validated. Therefore the objective was to construct the ISL and quantify the errors in measuring changes in position and orientation of the F-E axis.

The Qualitative Synthesis of Parallel Manipulators

2004 ◽  
Vol 126 (4) ◽  
pp. 617-624 ◽  
Author(s):  
Jorge Angeles
Keyword(s):  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Parallel Manipulators ◽  
Qualitative Reasoning ◽  
Rigid Bodies ◽  
Three Dimensions ◽  
Qualitative Synthesis ◽  
Motion Representation ◽  
Six Degrees Of Freedom ◽  
Three Degrees Of Freedom

As shown in this paper, when designing parallel manipulators for tasks involving less than six degrees of freedom, the topology can be laid out by resorting to qualitative reasoning. More specifically, the paper focuses on cases whereby the manipulation tasks pertain to displacements with the algebraic structure of a group. Besides the well-known planar and spherical displacements, this is the case of displacements involving: rotation about a given axis and translation in the direction of the same axis (cylindrical subgroup); translation in two and three dimensions (two- and three-dimensional translation subgroups); three independent translations and rotation about an axis of fixed direction, what is known as the Scho¨nflies subgroup; and similar to the Scho¨nflies subgroup, but with the rotation and the translation in the direction of the axis of rotation replaced by a screw displacement. For completeness, the fundamental concepts of motion representation and groups of displacements, as pertaining to rigid bodies, are first recalled. Finally, the concept of Π-joint, introduced elsewhere, is generalized to two and three degrees of freedom, thereby ending up with the Π2-and the Π3-joints, respectively.

Multiple-Body Collision Algorithms for Computational Simulation of High-Speed Air-Delivered Systems

2015 ◽  
Vol 17 (2) ◽  
pp. 564-593 ◽  
Author(s):  
Robert E. Harris ◽  
Peter A. Liever ◽  
Edward A. Luke ◽  
Jonathan G. Dudley
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Computational Simulation ◽  
Rigid Bodies ◽  
Flight Simulation ◽  
Dispersion Pattern ◽  
Reduced Order ◽  
Six Degrees Of Freedom ◽  
Collision Response ◽  
Engineering Level

AbstractCurrently, there exists a lack of confidence in the computational simulation of multiple body high-speed air delivered systems. Of particular interest is the ability to accurately predict the dispersion pattern of these systems under various deployment configurations. Classical engineering-level methods may not be able to predict these patterns with adequate confidence due primarily to accuracy errors attributable to reduced order modeling. In the current work, a new collision modeling capability has been developed to enable multiple-body proximate-flight simulation in the Loci/CHEM framework. This approach maintains high-fidelity aerodynamics and incorporates six degrees of freedom modeling with collision response, and is well-suited for simulation of a large number of projectiles. The proposed simulation system is intended to capture the strong interaction phase early in the projectile deployment, with subsequent transfer of projectile positions and flight states to the more economical engineering-level methods. Collisions between rigid bodies are modeled using an impulse-based approach with either an iterative propagation method or a simultaneous method. The latter is shown to be more accurate and robust for cases involving multiple simultaneous collisions as it eliminates the need to sort and resolve the collisions sequentially. The implementation of both the collision detection methodology and impact mechanics are described in detail with validation studies to demonstrate the efficiency and accuracy of the developed technologies. The studies chronologically detail the findings for simulating simple impacts and collisions between multiple bodies with aerodynamic interference effects.

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.

Control of processing at multi-tool two-support setup

2020 ◽  
pp. 67-73
Author(s):  
N.D. YUsubov ◽  
G.M. Abbasova
Keyword(s):  
Degrees Of Freedom ◽  
Factor Model ◽  
Angular Displacement ◽  
Factor Models ◽  
Technological System ◽  
Displacement Control ◽  
Model Accuracy ◽  
Six Degrees Of Freedom ◽  
Angular Displacements ◽  
And Control

The accuracy of two-tool machining on automatic lathes is analyzed. Full-factor models of distortions and scattering fields of the performed dimensions, taking into account the flexibility of the technological system on six degrees of freedom, i. e. angular displacements in the technological system, were used in the research. Possibilities of design and control of two-tool adjustment are considered. Keywords turning processing, cutting mode, two-tool setup, full-factor model, accuracy, angular displacement, control, calculation [email protected]

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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