A Five-Freedom Active Damping and Alignment Device Used in the Joule Balance

TL;DR

This paper introduces an active electromagnetic damping device for watt/joule balances that suppresses coil motions and reduces misalignment errors by controlling five degrees of freedom through feedback, improving measurement accuracy.

Contribution

The paper presents a novel five-freedom active damping device used outside the main magnet in joule balances, enhancing coil motion suppression and alignment correction.

Findings

Effective suppression of undesired coil motions.

Reduction of misalignment errors in measurements.

Demonstrated performance in both dynamic and static modes.

Abstract

Damping devices are necessary for suppressing the undesired coil motions in the watt/joule balance. In this paper, an active electromagnetic damping device, located outside the main magnet, is introduced in the joule balance project. The presented damping device can be used in both dynamic and static measurement modes. With the feedback from a detection system, five degrees of freedom of the coil, i.e. the horizontal displacement $x$, $y$ and the rotation angles $\theta_x$, $\theta_y$, $\theta_z$, can be controlled by the active damping device. Hence, two functions, i.e. suppressing the undesired coil motions and reducing the misalignment error, can be realized with this active damping device. The principle, construction and performance of the proposed active damping device are presented.