UC Irvine

This Ph.D. dissertation reports on the development of Coriolis vibratory gyroscopes and pedestrian inertial navigation algorithms, toward self-contained localization in environments where satellite signals and pre-installed infrastructure are unavailable. The motivating application is the localization of firefighters during structure fires, where dense smoke, elevated temperature, and no prior knowledge of the building rule out most navigation methods. The rapid drift of a dead-reckoning INS can be curtailed by the Zero-velocity UPdaTe (ZUPT), which estimates the inertial sensor biases during the stance-phase of the gait cycle. The accuracy of ZUPT-aided INS is therefore bounded by two complementary limitations: the noise performance of the yaw-axis gyroscope, which ZUPT cannot correct and sets the ceiling on achievable accuracy, and the reliability of the zero-velocity updates and system integration, which govern how closely that ceiling is met. This dissertation addresses these limitations as parallel advances toward a future integrated system rather than by building that system itself, and is organized in two parts: sensor development and system-level navigation.The first part advances transduction methods for the Dual-Shell Hemispherical Resonator Gyroscope (DSG). We developed a method to define electrodes for capacitive transduction within the bulk of the fused-silica of the resonator itself using Femtosecond Laser Induced Chemical Etching (FLICE), eliminating the separately fabricated electrode substrate and the assembly step it requires, and achieving bulk capacitive gaps as small as 5.5 µm on the DSG at a maximum as-fabricated quality factor of 4.57 million. We then demonstrated, to the best of our knowledge for the first time, operation of a microfabricated hemispherical resonator gyroscope as a rate gyroscope with no conductive film on the resonating element, replacing the drive, tune, and sense functions of metallization with indirect piezoelectric actuation, laser ablation trimming, and optical detection, and thereby avoiding the quality-factor degradation that metallization imposes. Finally, we established how the dual-shell geometry governs the efficiency of this indirect actuation, developing a modeling framework and characterizing five samples that together demonstrate a 6.5× improvement in displacement amplitude and a 12.3× improvement in quality-factor-normalized transduction efficiency over non-optimized designs. Each method was operated as a rate gyroscope, though none were incorporated into a navigation platform.The second part advances system-level navigation. We built a self-contained inertial navigation platform small enough to be embedded in the sole of a shoe, occupying 7.1 cm3 excluding battery and case, on which barometer-aided ZUPT-aided INS achieved a Circular Error Probable (CEP) of 0.66 m over a 125 m indoor walking trajectory. We then extended ZUPT to the crawling gaits of firefighter smoke-diving operations, for which the stationary interval assumed by conventional foot-mounted implementations is unreliable, by fusing shoe-and knee-mounted solutions in a joint filter coupled through a rigid-leg kinematic constraint and configured online by a random forest gait classifier. Over nine multi-gait trials with three subjects in full firefighter equipment, this reduced the horizontal CEP from 3.86 m to 0.58 m and the vertical root-mean-square error (RMSE) from 3.06 m to 1.26 m.Although developed toward a common goal, the two parts of this dissertation were not combined into a single experimental system: the DSG was not integrated into either navigation platform, and the navigation studies were conducted with commercial inertial measurement units (IMUs). The sensor development raises the achievable accuracy ceiling set by the yaw-axis gyroscope; the navigation developments improve how closely it is approached.