Guohong He

Bio: Guohong He is an academic researcher from University of Michigan. The author has contributed to research in topics: Gyroscope & Resonator. The author has an hindex of 9, co-authored 14 publications receiving 339 citations.

A single-crystal silicon vibrating ring gyroscope

Abstract: This paper reports a high-performance vibrating ring gyroscope fabricated in (111) oriented single-crystal silicon (SCS). High-performance microgyroscopes are needed in many applications, including inertial navigation, control, and defense/avionics/space. The ring gyroscope provides a number of advantages, including excellent mode matching, high-resolution, low zero-rate output, and long-term stability. In this paper, a SCS vibrating ring gyroscope with high aspect ratio silicon on glass structure was designed, fabricated and tested. The ring is 2.7mm in diameter and 150μm thick. The gyro has the following measured performance: high Q (12000), good nonlinearity (0.02%), large sensitivity (132 mV/°/sec), low output noise (10.4°/hr/Hz) and high resolution (7.2°/hr). The maximum bias shift is less than ±1°/sec over 10 hours without thermal control.

A single-crystal silicon vibrating ring gyroscope

Abstract: This paper reports a high-performance vibrating ring gyroscope fabricated in [111] oriented single-crystal silicon (SCS). High-performance microgyroscopes are needed in many applications, including inertial navigation, control, and defense/avionics/space. The ring gyroscope provides a number of advantages, including excellent mode matching, high-resolution, low zero-rate output, and long-term stability. In this paper, a SCS vibrating ring gyroscope with a high aspect ratio silicon on glass structure was designed, fabricated and tested. The ring is 2.7 mm in diameter and 150 /spl mu/m thick. The gyro has the following measured performance: high Q (12000), good nonlinearity (0.02%), large sensitivity (132 mV//spl deg//sec), low output noise (10.4/spl deg//hr//spl radic/(Hz)) and high resolution (7.2/spl deg//hr). The maximum bias shift is less than /spl plusmn/1/spl deg//sec over 10 hours without thermal control.

Microsystem device and methods for fabricating the same

Abstract: A microsystem includes a base layer formed from an electrical insulating material. The base layer has an inner surface defining a cavity and an external surface opposed to the inner surface, and in direct communication with an environment. A cap layer and a microelectromechanical (MEMS) device layer are formed from electrical insulating material or an other electrical insulating material. The cap has an inner surface defining a cavity, and an external surface opposed to the inner surface, and in direct communication with the environment. A MEMS device on/in the MEMS device layer is disposed between the base and the cap. Respective adjacent portions of the base, the cap and the device substrate are bonded to define an enclosed space. The enclosed space at least partially includes the base cavity or the cap cavity. At least a portion of a MEMS device on the device layer is in the enclosed space.

0.00016 deg/√hr Angle Random Walk (ARW) and 0.0014 deg/hr Bias Instability (BI) from a 5.2M-Q and 1-cm Precision Shell Integrating (PSI) Gyroscope

Abstract: We report record-high performance from a fused-silica micro Precision Shell Integrating (PSI) gyroscope. The PSI gyroscope uses a fused-silica resonator with a diameter of 1 cm and a mechanical quality factor (Q) of 5.2 million. The gyroscope has an angle random walk (ARW) of 0.00016 deg/√hr and short-term in-run bias instability of 0.0014 deg/hr without any temperature compensation. This performance for such a small shell gyroscope compares well with the larger mHRG and HRG devices reported previously. This performance, in a device this small, is achieved by optimizing the fabrication of the shell resonator so it provides high Q, large mass, high frequency resonance, and low as-fabricated frequency mismatch.

1.5-Million Q-Factor Vacuum-Packaged Birdbath Resonator Gyroscope (BRG)

Abstract: We report a vacuum-packaged fused-silica (FS) micro birdbath shell resonator gyroscope (BRG) with near-navigation-grade in-run (evaluation duration $ day) bias stability of 0.0103 deg/h (at room temperature without temperature stabilization). The BRG utilizes a 5mm diameter birdbath (BB) resonator with $n=2$ wineglass mode $f=10.5436\ \mathrm{kHz}$ and original frequency split $(\Delta f)=6\ \text{Hz}$ :. The BRG is encapsulated in an LCC package and has an excellent $Q$ (1.54 million) and decay time constant $(r=46\ \mathrm{s})$ after near mode matching. The performance is believed to be limited by the noise from readout-and-control circuitry. The bias stability of this device is among the best reported values for micro-scale vibratory gyroscopes today.

Noise analysis and characterization of a sigma-delta capacitive microaccelerometer

Abstract: This paper reports a high-sensitivity low-noise capacitive accelerometer system with one micro-g//spl radic/Hz resolution. The accelerometer and interface electronics together operate as a second-order electromechanical sigma-delta modulator. A detailed noise analysis of electromechanical sigma-delta capacitive accelerometers with a final goal of achieving sub-/spl mu/g resolution is also presented. The analysis and test results have shown that amplifier thermal and sensor charging reference voltage noises are dominant in open-loop mode of operation. For closed-loop mode of operation, mass-residual motion is the dominant noise source at low sampling frequencies. By increasing the sampling frequency, both open-loop and closed-loop overall noise can be reduced significantly. The interface circuit has more than 120 dB dynamic range and can resolve better than 10 aF. The complete module operates from a single 5-V supply and has a measured sensitivity of 960 mV/g with a noise floor of 1.08 /spl mu/g//spl radic/Hz in open-loop. This system can resolve better than 10 /spl mu/g//spl radic/Hz in closed-loop.

A monolithic three-axis micro-g micromachined silicon capacitive accelerometer

Abstract: A monolithic three-axis micro-g resolution silicon capacitive accelerometer system utilizing a combined surface and bulk micromachining technology is demonstrated. The accelerometer system consists of three individual single-axis accelerometers fabricated in a single substrate using a common fabrication process. All three devices have 475-/spl mu/m-thick silicon proof-mass, large area polysilicon sense/drive electrodes, and small sensing gap ( /spl sim/5 pF/g measured sensitivity and calculated sub-/spl mu/g//spl radic/Hz mechanical noise floor for all three axes. The total measured noise floor of the hybrid accelerometer assembled with a CMOS interface circuit is 1.60 /spl mu/g//spl radic/Hz (>1.5 kHz) and 1.08 /spl mu/g//spl radic/Hz (>600 Hz) for in-plane and out-of-plane devices, respectively.

The development of micro-gyroscope technology

Abstract: This review reports an overview and development of micro-gyroscope. The review first presents different types of micro-gyroscopes. Micro-gyroscopes in this review are categorized into Coriolis gyroscope, levitated rotor gyroscope, Sagnac gyroscope, nuclear magnetic resonance (NMR) gyroscope according to the working principle. Different principles, structures, materials, fabrications and control technologies of micro-gyroscopes are analyzed. This review compares different classes of gyroscopes in the aspects such as fabrication method, detection axis, materials, size and so on. Finally, the review evaluates the key technologies on how to improve the precision and anti-jamming ability and to extend the available applications of the gyroscopes in the market and patents as well.

The Development of Micromachined Gyroscope Structure and Circuitry Technology

Abstract: This review surveys micromachined gyroscope structure and circuitry technology The principle of micromachined gyroscopes is first introduced Then, different kinds of MEMS gyroscope structures, materials and fabrication technologies are illustrated Micromachined gyroscopes are mainly categorized into micromachined vibrating gyroscopes (MVGs), piezoelectric vibrating gyroscopes (PVGs), surface acoustic wave (SAW) gyroscopes, bulk acoustic wave (BAW) gyroscopes, micromachined electrostatically suspended gyroscopes (MESGs), magnetically suspended gyroscopes (MSGs), micro fiber optic gyroscopes (MFOGs), micro fluid gyroscopes (MFGs), micro atom gyroscopes (MAGs), and special micromachined gyroscopes Next, the control electronics of micromachined gyroscopes are analyzed The control circuits are categorized into typical circuitry and special circuitry technologies The typical circuitry technologies include typical analog circuitry and digital circuitry, while the special circuitry consists of sigma delta, mode matching, temperature/quadrature compensation and novel special technologies Finally, the characteristics of various typical gyroscopes and their development tendency are discussed and investigated in detail

Integrated Microelectromechanical Gyroscopes

Abstract: Microelectromechanical ~MEMS! gyroscopes have wide-ranging applications including automotive and consumer electronics markets. Among them, complementary metal-oxide semiconductor-compatible MEMS gyroscopes enable integration of signal condition- ing circuitry, multiaxis integration, small size, and low cost. This paper reviews various designs and fabrication processes for integrated MEMS gyroscopes and compares their performance. Operational principles and design issues of MEMS vibratory gyroscopes are also addressed.