Algorithm for Processing Signals of the Incremental Encoder for Calculating the Angles of Rotation of the Torsional Pendulum

В статье приведен алгоритм обработки сигналов инкрементного датчика для оценки свободных колебаний крутильного маятника при исследовании фрикционных характеристик смазочных материалов применительно к стальным канатам с использованием возможности ПО «PowerGraph». Стальной канат является сложной и гибкой стержневой системой, в которой проволоки имеют форму пространственной спирали (винтовой линии) или двойной спирали. При этом внутренние проволоки стальных канатов находятся внутри и недоступны для прямого исследования, измерения и контроля. Анализ фрикционных характеристик смазочных материалов, используемых в стальных канатах, усугубляется многокомпонентностью и сложной структурой объекта исследования. Экспериментальные методы исследования в этом случае представляют один из наиболее эффективных и достоверных способов оценки эксплуатационных свойств изделия в целом. В основу эксперимента положен процесс затухания вращательных колебаний тяжелого груза, висящего на исследуемом стальном канате. Используемый смазочный материал влияет на такой колебательный процесс, и характеристикой такого влияния является декремент затухания колебательного процесса. В качестве датчика угла использован инкрементный энкодер, установленный соосно исследуемому канату и обеспечивающий разрешение регистрации угла поворота до 0,18 градуса.

A torsional thrust stand for measuring the thrust response time of micro-Newton thrusters

Drag-free technology functions as the keystone for space-based gravitational wave detection satellites moving along a geodesic path, like the Laser Interferometer Space Antenna (LISA) Pathfinder, to achieve ultra-high microgravity level. Several prerequisites for micro-thrusters operated under the drag-free technique include constantly adjustable thrust, high resolution, low noise and fast response time. Accordingly, a torsional thrust measurement system was methodically devised to measure the thrust response time of such micro-thrusters on the ground. The characteristics of the dynamic thrust change with time are inverted by the angular displacement of the torsional pendulum, established by the dynamic equation of the same, thus, measuring the rise/fall time of the thrust applied to the torsional pendulum. Calibration of the torsional pendulum thrust measurement system is carried out by the standard electrostatic force generated by the electrostatic comb-drive or microelectromechanical actuator, facilitating the suitable identification of the pendulum parameters. Afterwards, the electrostatic and electromagnetic forces generated by the actuator are applied to validate the measurable thrust response time of the torsional thrust stand. The experimental results show that the above-mentioned thrust stand can effectively measure the thrust response time up to 10 ms for a thrust step in 10 s of micronewtons, which qualifies as the thrust response time required by micro-thrusters for space-based gravitational wave detection.

Characterizing viscoelastic properties of synthetic and natural fibers and their coatings with a torsional pendulum

Characterizing and understanding the viscoelastic mechanical properties of natural and synthetic fibers is of great importance in many biological and industrial applications. Microscopic techniques such as micro/nano indentation have been...

EXPERIMENTAL STUDY OF DAMPED OSCILLATIONS OF A TORSIONAL PENDULUM

A laboratory work methodic on the experimental study of damping torsion oscillations under educational laboratory conditions was developed in this article. A torsion pendulum, which is usually used for bullet flight speed experimental determination based on angular momentum, mechanical energy conservation laws, and the laws of natural oscillations patterns, was used for this purpose. A torsion pendulum is a rod suspended on a vertically stretched steel wire and capable of performing oscillatory motion in the horizontal plane. Two rectangle shaped bodies are attached at the rod's ends, also two identical cylindrical weights that can be moved, changing the inertia moment of the pendulum, and locked in a chosen position, are arranged on the steel rod. Damping parameter dependencies are studied: the damping coefficient, damping logarithmic decrement, relaxation time, amount of oscillations during relaxation and the mechanical system quality factor against pendulum inertia moment. The least squares method was used in the processing of the experimental results. The results from this experimental study prove theoretical dependencies fidelity. The method used in this study may be recommended for physical practicum at universities when there is not a finished installation for the damping of torsional oscillations.

A Computational Model of Vestibular Fluid Response to Human Body Rotation

A computational model was developed to study the response of vestibular fluid to body motions, relating eye movement to vestibular displacement. The response in the semicircular canals (SCCs) and otolith organs were approximated as a torsional pendulum and a forced wave equation, respectively. The results of the math model were found to be consistent with results found in previous models. The results of the model will also be compared to those found experimentally using VALUS, a rotational platform updated to be used for vestibular testing.