In this paper an excitation scheme employing simultaneous harmonic forcing and parametric excitation is applied to an electrostatically actuated MEMS gyroscope in order to improve the rate resolution performance to near inertial grade. A multiples scales perturbation method is used to investigate the dynamics of the gyroscope and facilitate in the design of a control methodology that enables the parametric pumping phenomena to the realized practically. The analysis shows that the quality factor of the primary mode of the gyroscope may be increased arbitrarily through parametric excitation. This allows forcing levels for the primary mode to be reduced by several orders of magnitude whilst sustaining the primary mode amplitude. Simulation of the oscillator scheme, which is highly non-linear, is achieved using MATLAB Simulink and is applied to a micro-ring gyroscope. The simulation demonstrates the Q-factor of the primary mode is increased by two orders of magnitude whilst the harmonic forcing amplitude is reduced by the same order, when the control scheme is operating. Agreement between the perturbation analysis and MATLAB Simulink models is within 8%. The increase in the Q-factor by two orders of magnitude results in a decrease in the electrical noise due to feedthrough by two orders of magnitude. This will enable a significant improvement of resonant gyroscope performance.
An optical workstation consisting of a surface profiler, laser vibrometer and a high power pulsed laser has been constructed for mechanical testing of MEMS. Through a series of static and dynamic measurements, the performance of a device is determined in seconds. For these measurements the device is induced to move by either using mechanical, electrostatic or optical actuation methods. In the latter case this is achieved by directing high power light pulses onto a silicon surface. The same laser can also be used to trim and frequency tune resonant devices. The workstation has been designed to incorporate single devices, wafers and packaged devices so that devices may be characterised at any stage of processing. The speed and non-contact nature of this workstation makes it suitable for industrial metrology. A variety of MEMS have been characterised, examples of which are presented. The workstation has also proved to be an invaluable tool for determining the cause of device failure in prototype designs.