The MicroGyro: A Quartz MEMS Automotive Gyroscope

Document Number: 2006-01-0143

Date Published: April 2006

Author(s):
Asad M. Madni - BEI Technologies Inc.
Lynn E. Costlow - BEI Systron Donner Automotive Division
Marc W. Smith - BEI Systron Donner Automotive Division

Abstract:
This paper describes the most recent automotive MEMS gyroscope by BEI Technologies, Inc., Systron Donner Automotive Division, known as the ƒÝGyro. This gyro combines advanced packaging, high performance, MEMS signal processing technology and self-monitoring during operation. Automotive sensors must meet performance requirements in the smallest package at an extremely low cost. Previous BEI gyros met performance, offered acceptable cost, but required multiple components with higher circuit board and assembly costs. This fifth generation product offers a single pick-and-place SMT package, incorporates BEI¡¦s ¡§hammerhead¡¨ quartz tuning fork and utilizes a new digital signal processing (DSP) ASIC. The ƒÝGyro minimizes analog circuits to achieve utmost stability versus age and low noise by digitizing the signal for DSP algorithm processing. An embedded microcontroller manages all functions and brings enhanced fault detection and monitoring capabilities at near zero cost. The ƒÝGyro features BEI¡¦s Continuous Built-In-Test (C-BIT) used for gyro self-monitoring during operation to augment system safety and reliability with a novel charge amplifier front-end. This device is designed for safety-critical automotive applications such as Electronic Stability Control (ESC), but is compliant with less stringent performance requirements, such as rollover airbag deployment. The ƒÝGyro outputs data over a SPI digital data bus and/or an analog output in either ratiometric or non-ratiometric mode. The analog output has a programmable output range and the digital data output has an extended angular rate range exceeding ¡Ó 800 deg/sec. The ƒÝGyro was developed for extended automotive ¡§under the hood¡¨ temperatures requiring operation up to 125¢XC. The hermetic packaging method draws from integrated circuit ceramic packaging techniques. The ASIC design utilizes aerospace inertial measurement unit DSP techniques pioneered by BEI. The paper will include details on the packaging and ASIC concepts in addition to performance data that is statistically relevant for this robust design.

File Size: 10266K
Product Status: In Stock

Included in: SP-2027

See other papers presented at SAE 2006 World Congress & Exhibition, April 2006, Detroit, MI, USA, Session: Intelligent Vehicle Initiative (IVI) Technology - Advanced Controls (Part 1 of 2)

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