Gyroscope angular rate processing across asynchronous clock domains

The Draper Laboratory requires a robust means of digital signal resampling for use in a microelectromechanical inertial measurement system. Complications arise because the complete inertial measurement unit requires a stable global time reference for the purposes of axis rate decoupling and integration, yet each gyroscope must adhere to an independent local time reference that is neither controllable nor known in advance. The digital interface between the host system and its component gyroscopes is therefore completely asynchronous. Asynchrony implies that sampling rate conversion is necessary, but also that the conversion ratio may be irrational or otherwise highly inconvenient. Traditional sampling rate conversion by rational fractions is thus impractical. This research examines several simple approaches to asynchronous resampling, then builds upon recent work to develop a flexible, efficient embedded resampling system. The new system utilizes a piecewise polynomial impulse response that may be designed to meet arbitrary frequency domain specifications using minimax linear programming methods. A detailed explanation of the design process is provided, along with a reference design implemented in VHDL. VI-A Company Thesis Supervisor: David J. McGorty Title: C.S. Draper Laboratory Principal Engineer M.I.T. Thesis Supervisor: Steven B. Leeb Title: Associate Professor of Electrical Engineering