Direct Angle Measurement Using Dynamically-Amplified Gyroscopes

This paper presents results on the instrumentation of a Dynamically-Amplified Gyroscope (DAG) for direct measurement of the absolute angle of rotation. Through a modal approximation method, we demonstrated that a 4-Degrees of Freedom (4-DoF) dual-mass DAG can be mathematically modeled as a conventional 2-DoF single-mass Coriolis Vibratory Gyroscope (CVG). Based on the single-mass-equivalent gyroscope characteristics derived using the reduced-order model, we compared the dynamics of the dual-mass DAG to other gyroscope architectures. Based on the analytical results, we conjectured that the established control architecture, developed for 2-DoF CVGs, can be adapted and applied to the 4-DoF DAG for angular rate and direct angle measurement. We tested this hypothesis by implementing the Whole-Angle (WA) control with a DAG device. Based on the reduced-order model, we measured the vibration of the outer mass to estimate the oscillation pattern, and control forces were calculated and applied to the drive mass to sustain the energy and reduce quadrature in the gyroscope. Through this approach, we successfully demonstrated the direct angle measurement capability of the DAG architecture. The corresponding characterization results on the angular gain, anisoelasticity, and anisodamping of the DAG are reported. With the DAG under test, we demonstrated an effective angular gain of 0.99, which is near the theoretical maximum angular gain of 1. The presented results supported the reduced-order model and demonstrated an approach for reducing the control complexity for the DAG and other gyroscope architectures with increased degrees of freedom.