| Modern control techniques such as mu-synthesis, sliding mode control and Sigma -- Delta modulation are finding new applications in the emerging field of microelectromechanical systems or MEMS. One such device is a directional microphone based on the auditory system of the parasitoid fly Ormia ochracea. In this thesis, feedback control was designed and verified in simulations to provide active damping of resonant frequencies in the system, and parameter uncertainty was taken into account in the formulation of a mu-synthesis framework to design a robust controller. A Sigma -- Delta control loop including the robust controller was analyzed and simulated. The purpose of the Sigma -- Delta control loop is to circumvent the nonlinearity of the electrostatic force used for actuation, and to digitize the signal for further digital processing. The Sigma -- Delta control loop successfully damped the uncertain resonance, and shaped the quantization noise from the oversampling operation. Finally, a sliding mode controller was designed to stabilize the system around an unknown operating point. |
