2014 International Symposium on Inertial Sensors and Systems (ISISS)

This paper describes ongoing efforts, sponsored by the U.S. Defense Advanced Research Projects Agency, Microsystems Technology Office (DARPA/MTO) to develop new technology that improves performance and reduces the Size, Weight, and Power (SWaP) of inertial navigation sensors. View full abstract»

This paper reports an order of magnitude reduction in frequency mismatch (ΔF) in polycrystalline diamond half-toroid resonators under development for use as microscale rate-integrating gyroscopes. The reduction in ΔF was achieved by eliminating the lip at the perimeter of the resonator. Measurements of resonance decay time as a function of frequency, temperature, and pressure are als... View full abstract»

A novel use of bulk metallic glasses in microresonator applications is reported and a method for the fabrication of ultra-smooth and highly symmetric three-dimensional wineglass structures with integrated electrode structures is presented. A shell with N=2 modes at 9.393 kHz and 9.401 kHz was characterized for both mounted and unmounted (to the electrode structure) conditions. Prior to mounting, t... View full abstract»

This paper reports analytical and finite element models for predicting the final 3-D geometry of micro-glassblown inverted-wineglass and hemi-toroidal structures from a set of initial conditions. Using these methods critical geometric param-eters for wineglass resonator and gyroscope operation, such as shell thickness, shell height, stem type (hollow/solid), and stem diameter can be estimated from... View full abstract»

Approximate closed-form solutions are developed for estimating the frequency separation caused by thickness, density, or radius azimuth variations in ring or hemispherical gyroscopes. For the nth flexural mode, frequency separation is caused by the 2n harmonic of density or thickness variation. These relations are combined with stochastic models to determine approximate closed-form solu... View full abstract»

The output variables of an MRIG (Microscale Rate Integrating Gyroscope), x, y, satisfy the equations of motion of a two-dimensional oscillator. (Ref. [1]) To examine the role of a mismatch of the two principal frequencies, ω1 and ω 2, we look at the response to a constant rate input, Ω, for times short compared to the damping time constants. Eqs. (7) of R... View full abstract»

Rate integrating gyroscopes measure angular rate by measuring the change in energy transfer between two orthogonal modes of vibration as rate is applied. Although these gyroscopes have the potential for high accuracy due to their direct measurement of angle, they are often hindered by material imperfections, the most significant of which are perturbations in stiffness within the material structure... View full abstract»

Inertial navigation provides a unique ability to know where one has been, where one is currently, and where one is going, given only a starting position. The laws of physics permit the sensing of dynamic motion without external information, making inertial systems impervious to jamming, masking, or spoofing. Measurements of six degrees of freedom are required - three linear accelerations, and thre... View full abstract»

Information on the Nuclear Magnetic Resonance Gyro under development by Northrop Grumman Corporation is presented. The basics of Operation are summarized, a review of the completed phases is presented, and the current state of development and progress in phase 4 is discussed. Many details have been left out for the sake of brevity, but the principles are still complete. View full abstract»

We present preliminary results of our research program towards multi-axis quantum acceleration sensors in a compact package, using Bloch oscillations of matter waves to provide large momentum transfer. The projected performance is discussed. We demonstrate the first Mach-Zehnder atom interferometer in which a cavity mode is used for addressing the atoms. View full abstract»

In a Coriolis Vibratory Gyro (CVG), two resonant modes of an elastic body that are uncoupled when the body is at rest exchange energy when the body rotates about a particular body-fixed axis. Highperformance CVGs are usually operated in either the force-rebalance mode in which the energy in one of the modes is nulled, the force required being proportional to the input rotation rate, or in the whol... View full abstract»

This paper reports on the design of a new monolithically integrated 3-axis high-g accelerometer. It is based on a 1D-sensor which exhibits a sensitivity of 0.65 μV/V/g and a resonant frequency of 1.5 MHz. Both figures are higher than for any piezoresistive high-g accelerometer in the literature or on the market and are due to an unconventional spring-mass-system geometry. The 3-axis acceler... View full abstract»

We report on the results of the experimental investigation of the relation between the dissipation and the type of actuation (different vibrational modes), of a novel tactical-grade single axis tuning fork gyroscope. We show that the quality factor limit measured at the skew-symmetric translation mode (Q=45000) is 40% lower than at the symmetric drive mode (Q=82000). The variation of the quality f... View full abstract»

This paper demonstrates that the Thermal Coefficient of resonant Frequency (TCF) of a micro glass-blown Pyrex spherical resonator can be substantially reduced by the application of a titanium (Ti) coating. Finite Elements Analysis (FEA) is used to demonstrate that the temperature dependence of the Young's modulus of the shell material is the dominant parameter affecting the TCF of the resonator, c... View full abstract»

This paper reports the experimental demonstration of Quality factor (Q-factor) improvement of fused quartz hemispherical resonators after post-fabrication annealing. Several identical fused quartz 3D hemispherical resonators, thickness 1 mm and diameter 10 mm were fabricated using micro-glassblowing process and tested before and after annealing. Results showed that annealing at 800 °C for 6... View full abstract»

This paper presents an adaptive notch filter to achieve more accurate demodulation variables in the method of averaging. The main advantage of this notch filter is a very sharp attenuation gain at twice of the estimated resonance frequency, which is the main frequency component of the oscillatory noise in the demodulated variables. The position of the sharp attenuation gain can be adjusted in real... View full abstract»

This paper presents an online adaptive controller to compensate damping and stiffness frequency mismatches in vibratory gyroscopes. This adaptive controller is running together with the method of averaging. The adaptive controller first estimates the effective damping and stiffness frequency mismatches using least square method and then compensates these estimated mismatches in an online fashion. ... View full abstract»

We present the detailed analysis of the orbital trajectory of Frequency Modulated (FM) gyroscopes, and the impact of this on the differential frequency output. The FM approach is based on tracking the resonant frequency split between two, high Q-factor mechanical modes of a Rate Integrating Gyroscope, for the purpose of producing a frequency-based measurement of the input angular rate. We show tha... View full abstract»

This paper's focus is a theoretical comparison of Nuclear Magnetic Resonance Gyroscope (NMRG) and Whole-Angle (WA) Coriolis Vibratory Gyroscopes (CVG) dynamics, showing the parallels in structure of basic equations and deriving performance scaling laws. The comparison relies on the method of averaging to derive the linearized equations of motion and analytical solutions for both types of sensors. ... View full abstract»

Over the past 15 years, inertial sensors have evolved at impressive rates and have contributed greatly to the field of human movement analysis. The Olympic athletes can gain valuable insight into key aspects of their performance through the use of such technology and engineering experts can contribute greatly to their success. This paper sheds some light on the important role that engineering expe... View full abstract»

This paper reports a batch-mode generic 3-D precision assembly and wafer-level packaging technology for 3-axis tri-fold inertial measurement units (IMUs) using silicon mounting jig wafers with embedded vacuum channels. This approach allows use of optimized single-axis IMUs without manufacturing and structural constraints of forming 3-axis in a chip, and improving the overall yield by testing the c... View full abstract»