This paper presents an electrostatic mechanism for tuning the temperature coefficient of frequency (TCf) of disk-shaped resonators fabricated in highly doped (100) single-crystalline silicon. Taking ...advantage of the degenerate nature of "wineglass" mode resonators such as rings and disks, we show that rotating the resonant mode shapes by electrostatically changing the boundary conditions can effectively tune the TCf. In this work, the proof-of-concept is demonstrated by matching the TCf of the drive and sense modes of a disk resonator gyroscope (DRG). By using electrostatic tuning, the two wineglass modes are each rotated by 22.5° from the natural 0° and 45° (with respect to <;110>) positions, resulting in a substantial reduction in the TCf mismatch between two modes. The capability to tune TCf of wineglass mode resonators has potential applications for not only continuous mode-matching operation of vibratory gyroscopes, but also temperature compensation of silicon-based MEMS oscillators.
This work demonstrates, for the first time, ovenization of a fully-encapsulated dual-mode silicon MEMS resonator operational over a large ambient temperature range. We maintain a localized, elevated ...operating temperature by utilizing the temperature coefficient of frequency (TCf) difference between two excitation modes of the same resonant body as a thermometer, and by integrating a micro-oven in the encapsulation layer. Preliminary results of real-time compensation demonstrate a stability of ±250ppb of the in-plane Lamé-mode frequency over -20°C to 80°C.
This paper reports a miniature Inertial Measurement Unit (IMU) implemented using a folded MEMS approach which allows for integration of high performance sensors, while providing a low cross-talk ...between the components. Foldable Si structures are manufactured on a wafer-level using MEMS techniques, co-fabricated or integrated with single-axis inertial sensors and then folded into a 3D configuration, forming the complete IMU. Electrical signals from the sensors on sidewalls of the IMU Cube are transferred through the dense network of metal traces on parylene, thus enabling the integration with signal processing electronics. For the first time, we characterized cross-talk between sensors on a folded 3D IMU. The experimental results provided an evidence that the folded IMU process is advantageous to a single-die approach, showing a lower Angle Random Walk (ARW) of the gyroscopes when operated simultaneously on different sidewalls of the IMU Cube.
This paper demonstrates the effect of nonlinear elasticity on the coupling between different bulk modes of silicon MEMS resonators. From experimental data, we observe that the coupling has a strong ...dependence on the resonant mode order, the mode shape of the coupled modes, as well as the doping type / concentration, and crystal orientation, leading to a variety of complex and potentially useful phenomena.
Vision Based Mapping and Localization in Unknown Environment for Intelligent Mobile Robot Xiaoxin Qiu; Hong Lu; Wenqiang Zhang ...
2014 IEEE 11th Intl Conf on Ubiquitous Intelligence and Computing and 2014 IEEE 11th Intl Conf on Autonomic and Trusted Computing and 2014 IEEE 14th Intl Conf on Scalable Computing and Communications and Its Associated Workshops,
12/2014
Conference Proceeding
Simultaneous Localization and Mapping (SLAM) is a key component of mobile robot's navigation. In this paper, we present a vision-based system of mapping and localization. The system builds a map ...which contains 3D landmarks of environment. 3D landmarks are reconstructed based on sequential Harris Corner Features. In order to match regained features with landmarks in the map, we present a simple method, i.e. Inverse Projection. The method is relatively simple and effective. We also propose an efficient observe model that simplifies the Jacobian Matrix when apply the Extended Kalman Filter (EKF) framework. We conduct experiments in both simulation and real-time environment, and give error analysis for robot's and landmarks' position. Experiment results show that landmarks are localized accurately and robot trajectory is well estimated by matched landmarks.
In this study we demonstrate for the first time integration of differential internal electrodes into a Disk Resonator Gyroscope (DRG) design within a wafer-scale encapsulation process. The ...differential internal electrodes design enables the mode-matching operation of the device with low DC power supplies (±5 V) thanks to the enhanced transduction area, while maintaining similar performance to the previously reported baseline DRG. The mode-matching operation yields a scale-factor of 1.37 mV/(7s) and an ARW of 0.29 °/√hr.
A unified epi-seal process for resonators and inertial sensors Yang, Yushi; Ng, Eldwin J.; Yunhan Chen ...
2015 Transducers - 2015 18th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS),
06/2015
Conference Proceeding
A thin-film wafer-level encapsulation process which incorporates both narrow (0.7 μm) and wide (>50 μm) lateral transduction gaps, in-plane and out-of-plane electrodes, and does not require release ...etch-holes is presented. High stability, high quality factor (Q) resonant devices as well as inertial sensors are fabricated in the process. The great diversity of functioning devices built in this process demonstrates the potential for combinations of high-performance MEMS devices in a single process and even in single chips.
In whole body PET scanners, extending the axial field of view (AFOV) can significantly increases the sensitivity. However, image axial resolution, which is an essential criterion in whole-body PET, ...may be especially affected by the depth of interaction (DOI) as the AFOV increases. In this paper, we use Monte Carlo simulations to find, in a long axial-FOV PET how DOI information affects the axial resolution. We also compared the axial resolution in scanners with only different AFOV ranging from 158 mm to 360 mm. All axial resolutions were measured as a function of ring difference (sensitivity) both with and without DOI information. The simulation study shows that as AFOV increases the axial spatial resolution gets worse much more quickly compared with that in transverse direction and in the scanner with largest AFOV (360 mm), introduction of DOI improves axial resolution by 12.28%. Besides, the introduction of DOI information can significantly increase the sensitivity performance by up to 37.5% when the axial resolution is fixed to 1cm because a DOI PET system allows more oblique events to be used in the image reconstruction.
This paper reports, for the first time, over-travel stops actively driven into resonance to help overcome stiction forces between contacting silicon surfaces. By resonating over-travel stops during ...contact with proof masses, we show that effective adhesion forces are decreased by over 60% compared to cases with static bump stops. Furthermore, by monitoring shift in resonant frequency during contact, we present a novel way to determine adhesion forces, even within fully encapsulated devices, where other measurement methods are unavailable.
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