Jie Luo,¹ Wei-Huang Wu,¹ Chao Xue,^2,3 Cheng-Gang Shao,²Wen-Ze Zhan,¹ Jun-Fei Wu,² and Vadim Milyukov⁴

¹School of Mechanical Engineering and Electronic Information, China University of Geosciences, Wuhan 430074, People’s Republic of China

²MOE Key Laboratory of Fundamental Physical Quantities Measurement, School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People’s Republic of China

³School of Physics and Astronomy, Sun Yat-sen University, Guangzhou 510275, People’s Republic of China ⁴Sternberg Astronomical Institute, Lomonosov Moscow State University, Moscow 119992, Russia

(Received 9 May 2016; accepted 22 July 2016; published online 10 August 2016)

In the measurement of the gravitational constant G with angular acceleration method, the equilibrium position of torsion pendulum with tungsten fiber undergoes a linear slow drift, which results in a quadratic slow drift on the angular velocity of the torsion balance turntable under feedback control unit. The accurate amplitude determination of the useful angular acceleration signal with known frequency is biased by the linear slow drift and the coupling effect of the drifting equilibrium position and the room fixed gravitational background signal. We calculate the influences of the linear slow drift and the complex coupling effect on the value of G, respectively. The result shows that the bias of the linear slow drift on G is 7 ppm, and the influence of the coupling effect is less than 1 ppm. Published by AIP Publishing. [http://dx.doi.org/10.1063/1.4960398]