scholarly journals Three Degrees-of-Freedom Optical Spindle Error Motion Measurement Device

2017 ◽  
pp. 1471
Keyword(s):  
Degrees Of Freedom ◽  
Measurement Device ◽  
Motion Measurement ◽  
Error Motion ◽  
Three Degrees Of Freedom

scholarly journals A Measurement Device for Rotational Stiffness of the Eye

2008 ◽  
Vol 2 (2) ◽  
Author(s):  
Thijs R. de Graaf ◽  
Sander Schutte ◽  
Huib J. Simonsz ◽  
Arthur G. Erdman ◽  
Frans C. T. van der Helm ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Degrees Of Freedom ◽  
Strabismus Surgery ◽  
Horizontal Position ◽  
Linkage Mechanism ◽  
Rotational Stiffness ◽  
Measurement Device ◽  
Interindividual Differences ◽  
Outcome Of Surgery ◽  
Three Degrees Of Freedom

Objective: A measurement of rotational stiffness of the human eye is necessary, without exerting forces to the eye. Background: Strabismus is a disorder in which the visual axes of the eyes are misaligned. In strabismus surgery, the muscles that drive the eye are altered to compensate for the deviating angle of the eye. Unfortunately, between 20% and 50% of these operations need resurgery. A sensitivity analysis has suggested that one cause for an erroneous outcome of surgery is due to interindividual differences in rotational stiffness induced by tissue surrounding the eye. Methods and Results: A measurement device comprising a moment transferring linkage mechanism was developed. A moment is transferred to the eye without imposing a stationary point of rotation. The mechanism is attached to the eye and has three degrees of freedom. The eye is free to rotate under the applied moment. The applied moment and the resulting angle are measured to calculate the rotational stiffness of the eye. Parasitic forces are minimized by keeping friction, inertia and stiffness in the mechanism to a minimum. In addition, the three degrees of freedom of the mechanism are statically balanced. Conclusion: Preliminary tests have shown the feasibility of the measurement in a sterile environment in people that are in horizontal position.

scholarly journals Active Disturbance Rejection for a Three Degrees of Freedom Gyroscope

2018 ◽  
Vol 51 (13) ◽  
pp. 372-377 ◽  
Author(s):  
Juan E. Andrade García ◽  
Alejandra Ferreira de Loza ◽  
Luis T. Aguilar ◽  
Ramón I. Verdés
Keyword(s):  
Disturbance Rejection ◽  
Degrees Of Freedom ◽  
Active Disturbance Rejection ◽  
Three Degrees Of Freedom

scholarly journals Cyclic Deformation of Microcantilevers Using In-Situ Micromanipulation

2021 ◽  
Author(s):  
A. H. S. Iyer ◽  
M. H. Colliander
Keyword(s):  
Degrees Of Freedom ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Structural Components ◽  
Cyclic Testing ◽  
Phase Boundaries ◽  
Bulk Specimen ◽  
Arbitrary Position ◽  
Three Degrees Of Freedom

Abstract Background The trend in miniaturisation of structural components and continuous development of more advanced crystal plasticity models point towards the need for understanding cyclic properties of engineering materials at the microscale. Though the technology of focused ion beam milling enables the preparation of micron-sized samples for mechanical testing using nanoindenters, much of the focus has been on monotonic testing since the limited 1D motion of nanoindenters imposes restrictions on both sample preparation and cyclic testing. Objective/Methods In this work, we present an approach for cyclic microcantilever bending using a micromanipulator setup having three degrees of freedom, thereby offering more flexibility. Results The method has been demonstrated and validated by cyclic bending of Alloy 718plus microcantilevers prepared on a bulk specimen. The experiments reveal that this method is reliable and produces results that are comparable to a nanoindenter setup. Conclusions Due to the flexibility of the method, it offers straightforward testing of cantilevers manufactured at arbitrary position on bulk samples with fully reversed plastic deformation. Specific microstructural features, e.g., selected orientations, grain boundaries, phase boundaries etc., can therefore be easily targeted.

scholarly journals Galloping Stability and Wind Tunnel Test of Iced Quad Bundled Conductors considering Wake Effect

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Xiaohui Liu ◽  
Ming Zou ◽  
Chuan Wu ◽  
Mengqi Cai ◽  
Guangyun Min ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Transmission Lines ◽  
Degrees Of Freedom ◽  
Wind Tunnel Test ◽  
Aerodynamic Coefficients ◽  
Wake Effect ◽  
Aerodynamic Coefficient ◽  
Set Up ◽  
The Stability ◽  
Three Degrees Of Freedom

A new quad bundle conductor galloping model considering wake effect is proposed to solve the problem of different aerodynamic coefficients of each subconductor of iced quad bundle conductor. Based on the quasistatic theory, a new 3-DOF (three degrees of freedom) galloping model of iced quad bundle conductors is established, which can accurately reflect the energy transfer and galloping of quad bundle conductor in three directions. After a series of formula derivations, the conductor stability judgment formula is obtained. In the wind tunnel test, according to the actual engineering situation, different variables are set up to accurately simulate the galloping of iced quad bundle conductor under the wind, and the aerodynamic coefficient is obtained. Finally, according to the stability judgment formula of this paper, calculate the critical wind speed of conductor galloping through programming. The dates of wind tunnel test and calculation in this paper can be used in the antigalloping design of transmission lines.

Analysis and Optimization of a New Differentially Driven Cable Parallel Robot

2015 ◽  
Vol 7 (3) ◽  
Author(s):  
Hamed Khakpour ◽  
Lionel Birglen ◽  
Souheil-Antoine Tahan
Keyword(s):  
Kinematic Analysis ◽  
Design Methodology ◽  
Degrees Of Freedom ◽  
Parallel Robot ◽  
Cable Robot ◽  
Proper Design ◽  
Two Indices ◽  
Three Degrees Of Freedom ◽  
Cable Robots

In this paper, a new three degrees of freedom (DOF) differentially actuated cable parallel robot is proposed. This mechanism is driven by a prismatic actuator and three cable differentials. Through this design, the idea of using differentials in the structure of a spatial cable robot is investigated. Considering their particular properties, the kinematic analysis of the robot is presented. Then, two indices are defined to evaluate the workspaces of the robot. Using these indices, the robot is subsequently optimized. Finally, the performance of the optimized differentially driven robot is compared with fully actuated mechanisms. The results show that through a proper design methodology, the robot can have a larger workspace and better performance using differentials than the fully driven cable robots using the same number of actuators.

In-situ high-pressure study of the ordered phase of ethyl propionate

2007 ◽  
Vol 63 (1) ◽  
pp. 111-117 ◽  
Author(s):  
Roman Gajda ◽  
Andrzej Katrusiak
Keyword(s):  
High Pressure ◽  
Degrees Of Freedom ◽  
Molecular Volume ◽  
Ethyl Propionate ◽  
Intermolecular Contacts ◽  
High Pressure Study ◽  
Pressure Phase ◽  
Three Degrees Of Freedom ◽  
Volume Difference

Ethyl propionate, C5H10O2 (m.p. 199 K), has been in-situ pressure-frozen and its structure determined at 1.34, 1.98 and 2.45 GPa. The crystal structure of the new high-pressure phase (denoted β) is different from phase α obtained by lowering the temperature. The freezing pressure of ethyl propionate at 296 K is 1.03 GPa. The molecule assumes an extended chain s-trans–trans–trans conformation, only slightly distorted from planarity. The closest intermolecular contacts in both phases are formed between carbonyl O and methyl H atoms; however, the ethyl-group H atoms in phase β form no contacts shorter than 2.58 Å. A considerable molecular volume difference of 24.2 Å3 between phases α and β can be rationalized in terms of degrees of freedom of molecules arranged into closely packed structures: the three degrees of freedom allowed for rearrangements of molecules confined to planar sheets in phase α, but are not sufficient for obtaining a densely packed pattern.

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