Spin-torque sensor with tunable sensitivity and detection range

We propose a sensor consisting of small-sized coils connected in series and a detection method for the sensor based on the iteration of the periodic time difference. The evaluation results are also presented and show the effectiveness of the proposed system. The target performance of the sensor is as follows: (i) a detection range from 0 to ±100 Nm, (ii) a hysteresis error of less than 1%, (iii) an angular-dependent noise of less than 2%, and (iv) a sensor drift of less than 2%. From the evaluation results, it is clear that these performance targets, as well as a sufficient response time, are realized.

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Design of a Non-Contact Radial Torque Sensor with Variable Torque Range by Electromagnetic Coil Coupling with Piezoelectric Sensor

Materials ◽

10.3390/ma14247695 ◽

2021 ◽

Vol 14 (24) ◽

pp. 7695

Author(s):

Sheng-He Wang

Keyword(s):

Magnetic Force ◽

Piezoelectric Sensor ◽

Torque Sensor ◽

Detection Range ◽

External Torque ◽

Electromagnetic Coil ◽

Beam Mechanism ◽

The Moment ◽

Monitoring Technologies ◽

Automation Technology

Recently, due to the development of automation technology, torque measuring and monitoring technologies have been brought to the focus. However, the commercially available sensors have the disadvantage of large volume, which results in the difficulty of installation on existing automated machines. Responding to the above-mentioned problem, a contactless torque sensor that uses an electromagnetic coil combined with a permanent magnet was proposed. By adjusting the input electric current in the coil, the strength of the magnetic field can be controlled to generate a non-contact magnetic force to resist external torque loading. For the measurement of such a magnetic force, a cantilever-beam mechanism comprising a piezoelectric-loading (PZT-L) sensor is employed to estimate the external static force by measuring the variation of the electric impedance. According to the measured results, the proposed PZT-L sensor demonstrates the accuracy of the proposed design, for which the maximum estimated error was around 6%. Finally, the proposed contactless torque sensor with 11 cm in diameter and 2 cm in thickness was employed to verify the effectiveness of theoretical analysis. From the sensor characteristic measurement, the detection range for external torque can be from 7.8 to 125.6 N-mm when the driven current input ranged from 2 to 10 A. Therefore, the experimental results presented that the moment of inertia via the resisted torque can be adjusted by the proposed non-contact torque-sensing system according to the measuring condition.

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Seti Figure of Merit

International Astronomical Union Colloquium ◽

10.1017/s0252921100015293 ◽

1997 ◽

Vol 161 ◽

pp. 711-717 ◽

Cited By ~ 1

Author(s):

John W. Dreher ◽

D. Kent Cullers

Keyword(s):

Figure Of Merit ◽

Qualitative Difference ◽

Current Generation ◽

Detection Range ◽

Sky Surveys ◽

Independent Observations ◽

Good For

AbstractWe develop a figure of merit for SETI observations which is anexplicitfunction of the EIRP of the transmitters, which allows us to treat sky surveys and targeted searches on the same footing. For each EIRP, we calculate the product of terms measuring the number of stars within detection range, the range of frequencies searched, and the number of independent observations for each star. For a given set of SETI observations, the result is a graph of merit versus transmitter EIRP. We apply this technique to several completed and ongoing SETI programs. The results provide a quantitative confirmation of the expected qualitative difference between sky surveys and targeted searches: the Project Phoenix targeted search is good for finding transmitters in the 109to 1014W range, while the sky surveys do their best at higher powers. Current generation optical SETI is not yet competitive with microwave SETI.

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АКУСТИЧНА ПОМІТНІСТЬ БЕЗПІЛОТНИХ ЛІТАЛЬНИХ АПАРАТІВ З СИЛОВИМИ УСТАНОВКАМИ НА БАЗІ ПОРШНЕВИХ ДВИГУНІВ

Open Information and Computer Integrated Technologies ◽

10.32620/oikit.2020.88.05 ◽

2020 ◽

pp. 62-80

Author(s):

В. В. Руденко ◽

И. В. Калужинов ◽

Н. А. Андрущенко

Keyword(s):

Control System ◽

Internal Combustion Engine ◽

Power Plants ◽

Combustion Engine ◽

Spectral Characteristics ◽

Experimental Studies ◽

Internal Combustion ◽

Detection Range ◽

Acoustic Signature ◽

Static Conditions

The presence in operation of many prototypes of UAVs with propeller propellers, the use of such devices at relatively low altitudes and flight speeds makes the problem of noise reduction from UAVs urgent both from the point of view of acoustic imperceptibility and ecology.The aim of the work is to determine a set of methods that help to reduce the visibility of UAVs in the acoustic range. It is shown that the main source of noise from the UAV on the ground is the power plant, which includes the engine and the propeller. The parameters of the power plants influencing the processes that determine the acoustic signature of the UAV were investigated. A comprehensive analysis of the factors affecting visibility was carried out. The power plants include two-stroke and four-stroke engines, internal combustion and two-blade propellers. The use of silencers on the exhaust of the internal combustion engine was considered. The spectral characteristics of the acoustic fields of the propeller-driven power plants for the operating sample of the UAV "Eco" were obtained. The measurements were carried out in one-third octave and 1/48 octave frequency bands under static conditions. The venue is the KhAI airfield. Note that the propellers that were part of the power plants operated at Reynolds numbers (Re0,75<2*105), which can significantly affect its aerodynamic and acoustic characteristics. It is shown that when choosing a UAV control system, one should take into account the fact that two-stroke piston engines are the dominant source in the noise of propeller-driven control systems in the absence of a hood and mufflers in the intake and exhaust tracts. The use of a four-stroke internal combustion engine significantly reduces the noise of the control system. In the general case, the position of the boundaries of the zone of acoustic visibility of a UAV at the location of the observer is determined by the ratio between the intensity of acoustic radiation perceived by the observer from the UAV and the intensity of sound corresponding to the natural acoustic background and depends on the degree of manifestation of acoustic effects accompanying the propagation of sound in a turbulent atmosphere - the refraction of sound waves. Absorption and dissipation of acoustic energy. The calculation and comparison of the UAV detection range was carried out taking into account the existing natural maskers.The results of experimental studies are presented that allow assessing the degree of acoustic signature of the UAV. A set of measures aimed at reducing the intensity of the acoustic signature of the UAV in various regions of the radiation spectrum has been determined.

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