A control scheme for a MEMS electrostatic resonant gyroscope excited using combined parametric excitation and harmonic forcing

In this paper, a method employing both parametric excitation and harmonic forcing is applied to the excitation of a micro-ring gyroscope in order to improve its rate resolution performance. A multiple scales perturbation method is used to propose a methodology and this demonstrates the significance of the parametric instability boundary in facilitating the design of the required control strategies. The analysis shows that the 'effective' quality factor of any mode of vibration of the resonator may be increased arbitrarily through parametric excitation. This scheme, when applied to the primary motion of the gyroscope, allows forcing levels to be reduced by several orders of magnitude whilst sustaining the response amplitude. As the parametric excitation and forcing are at different frequencies the excitation scheme proposed minimizes the unwanted effect of electrical 'feedthrough' at the forcing frequency, resulting from parasitic capacitances. Simulation of the oscillator scheme, which is highly nonlinear, is achieved using MATLAB-Simulink and this validates the perturbation analysis. Agreement between the models within 8% is demonstrated. The excitation scheme proposed may be readily applied to many resonant MEMS/NEMS sensors.