Investigation of air damping in different vibrational modes of lateral-axis gyroscopes

This paper presents an analytic, numerical and experimental study of air damping behavior of lateral-axis vibratory wheel gyroscopes (VWG) in vacuum range of 0.008Pa to 10Pa. An analytic model is proposed for slide film damping in drive mode, and a Reynolds equation solved by a finite-difference method is employed for squeeze film damping in sense mode. The developed models are verified by experiment results for a lateral-axis VWG with resonant frequency around 10kHz. It is the first time to find that in the lateral-axis VWG, with pressure decreasing, the main energy loss will transform from air damping to non-viscous energy dissipations (including thermal-elastic damping (TED), anchor loss, etc.) at the critical pressure points of 0.85Pa and 0.4Pa, in drive and sense modes respectively. The calculated Q-factors are within +/-15% of the measured value when non-viscous energy dissipation mechanisms are included.