Earth Rate Detection and Gyrocompassing Mechanics for Gyroscope Alignment
Detecting Earth rotation rate for north alignment demands gyro bias stability below 0.05 degrees per hour and accelerometer tilt correction within 0.1 mrad.
Quad Mass MEMS Resonator
Structural Architecture
Suspension of four identical, symmetrically arranged micro-machined silicon masses on flexible beams provides an extremely stable platform for high-performance Coriolis vibratory gyroscopes. Utilizing a quad mass mems resonator reduces susceptibility to external vibrations and mounting stresses. The four masses are driven to oscillate in a balanced, anti-phase pattern that keeps the system’s center of mass stationary.
This internal balance prevents energy from leaking into the substrate, thereby maximizing the mechanical quality factor of the device.
Vibration Balance
This unique anti-phase oscillation pattern creates a high-Q mechanical system that is highly isolated from outside energy. Linear acceleration affects all four masses equally, which cancels out their net force on the sense electrodes and protects the gyroscope from vibration-induced drift.
Symmetric Cancellation
Misalignment errors and mechanical quadratures are significantly minimized by the symmetric geometry of the four moving masses. By distributing the resonant energy evenly across the structure, the sensor achieves exceptional bias stability over long operational periods. This architecture helps the gyroscope maintain its accuracy in demanding industrial or tactical applications.
Thermal Response
Small differences in thermal expansion between the silicon and the ceramic package can still introduce localized stress. However, the symmetric layout ensures that these forces are distributed evenly, which prevents the sensor from experiencing asymmetric deformations that would skew the output.