A Disturbance Rejection Method for Beam Balance Oscillation Period Measurement

Precision measurement of the oscillation period of a beam balance oscillator has a fundamental role in the inertial mass measurement project. In order to improve the accuracy of oscillation period measurement, the nonlinear oscillation theory is used to study the periodic oscillation process of the beam balance oscillator in this paper, and the analytical solutions of the dynamic equations of the balance under free and forced conditions are deduced. Moreover, the effects of ground vibration, air turbulence, and temperature fluctuation on the accuracy of oscillation period measurement are analyzed in detail in both vacuum and atmospheric environments, and a method based on beam structural parameters adjustment and temperature coefficient correction is proposed to suppress these disturbances under air condition. Experimental results show that the relative standard uncertainty of the measured oscillation period can be reduced from 2.5×10
^-5
to 1.2×10
^-6
(Class A, k =1) after the above-mentioned method is adopted.