Static phase improvements in the LNE watt balance

Pinot, P.; Espel, Patrick; Liu, Y.; Thomas, Matthieu; Ziane, Djamel; Palacios-Restrepo, M.-A.; Piquemal, F.

doi:10.1063/1.4964293

Cited by 8 publications

(8 citation statements)

References 27 publications

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“…Numerical simulations show that the beam arm bending is of the order of 40 µm with a 60 N load distributed equally on each arm (as it is in the experimental set-up) [25].…”

Section: Alignment Of the Pivots Of The Balance Beammentioning

confidence: 99%

“…A single-piece beam with two symmetrical 100 mm length arms and having three flexure pivots has been designed [25].…”

Section: A Balance Beam Fixed To the Lower Plate Of The Guiding Stagementioning

confidence: 99%

“…A single-piece beam from a special aluminum alloy EN AW-7075 T651 has been designed [25]. To fix the position of the rotation axes, the three flexures hinges formed by symmetrical 40 µm thick bi-concave profiles and are machined in the same metal block as that of the beam in such a way that, once the beam is loaded, the rotation axes are by construction parallel and coplanar.…”

Section: Alignment Of the Pivots Of The Balance Beammentioning

confidence: 99%

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A determination of the Planck constant using the LNE Kibble balance in air

et al. 2017

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“…Numerical simulations show that the beam arm bending is of the order of 40 µm with a 60 N load distributed equally on each arm (as it is in the experimental set-up) [25].…”

Section: Alignment Of the Pivots Of The Balance Beammentioning

confidence: 99%

“…A single-piece beam with two symmetrical 100 mm length arms and having three flexure pivots has been designed [25].…”

Section: A Balance Beam Fixed To the Lower Plate Of The Guiding Stagementioning

confidence: 99%

Section: Alignment Of the Pivots Of The Balance Beammentioning

confidence: 99%

See 1 more Smart Citation

A determination of the Planck constant using the LNE Kibble balance in air

et al. 2017

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“…However, this ideal alignment status is difficult to achieve, and alignment * Authors to whom any correspondence should be addressed. errors caused by parasitic forces and torques appear [8][9][10][11][12][13][14][15]. The error in alignment is one of the main sources of uncertainty in the joule and Kibble balances.…”

Section: Introductionmentioning

confidence: 99%

Automatic alignment technique for the suspended coil in the joule balance

Bai¹,

Wang²,

Li³

et al. 2021

Metrologia

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An automatic alignment technique was developed for the joule balance to reduce the uncertainty caused by alignment errors. Using the flexures and decoupling structure of the suspended coil, the proposed alignment system can automatically recognize the linear relationship between the initial position and posture of the suspended coil when the current is off, and its parasitic horizontal linear and angular displacements when the current is on. Subsequently, several actuators including mini-motors and an X-Y stage are controlled to adjust the position and posture of the coil, minimizing the parasitic forces and torques and reducing them by approximately 100 times in comparison with the alignment results of the joule balance obtained in 2019, whilst maintaining the adjustment time to several minutes only.

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“…To prevent the large deflection of flexure due to deadweights, a counterweight is normally applied, as shown in figure 1. Nevertheless, the use of a counterweight induces a high mean stress in the flexure hinges, which can lead to fracture and fatigue failure [13,14]. Consequently, the EMFC weighing cell is vulnerable to impact or overweight.…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic force compensation weighing cell with magnetic springs and air bearings

Yoon

Park

Choi

2020

Meas. Sci. Technol.

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The electromagnetic force compensation (EMFC) principle is a state-of-the-art weighing method for precision mass measurement. In this method, the low stiffness of the flexure-based Roberval guide mechanism and high lever ratio of force transmission contribute to achieving extremely high weighing sensitivity. However, weak damping and the parasitic resonant frequencies of the flexure mechanism lead to a slow settling time after loading a weight. Moreover, the low ruggedness of the flexure mechanism limits the load capacity of the EMFC weighing cell and may result in fatigue failure under repeated loading. In this paper, we propose a novel precision weighing cell with Halbach array magnetic springs and air bearings instead of the flexure mechanism. The magnetic spring is designed for near-zero negative stiffness to increase the system bandwidth, as well as for gravity force compensation ability against deadweights. The air bearings ensure high ruggedness toward parasitic directions with high stiffness in the parasitic direction and a damping effect from the pressurized air film. The stiffness of the fabricated prototype weighing cell is −27.3 N m−1, which is tens of times lower than that of conventional EMFC weighing cells. The weighing repeatability of the weighing cell is 2.35 mg, as measured with a 10 g E2 class test mass, and the settling time within ±2% of its final value is 57 ms in air.

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Static phase improvements in the LNE watt balance

Cited by 8 publications

References 27 publications

A determination of the Planck constant using the LNE Kibble balance in air

A determination of the Planck constant using the LNE Kibble balance in air

Automatic alignment technique for the suspended coil in the joule balance

Electromagnetic force compensation weighing cell with magnetic springs and air bearings

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