The Rugged Gyro in Automotive Application

Published:2011/9/6 4:16:00 Author:Li xiao na From:SeekIC

In order to eliminate the acceleration errors in automotive dynamics control, the Analog devices has moved to quad gyros.

The ADXRS800 is an angular rate sensor, which can be applied intended for automotive electronic stability control, vehicle rollover detection, and other high performance applications. An advanced, differential, quad-sensor design rejects the influence of linear acceleration, enabling the ADXRS800 to run in exceedingly harsh environments where shock and vibration are present. With this component, the architecture senses angular rates increase to +/-300°/s with 80LSB/°/s resolution while simultaneously providing linear acceleration rejection with cross-talk of only 0.03°/s/gravity.The self-test is embedded in, and the on-chip mechanical structures is inside the loop.

A stability control system needs accurate inertial signals at all times, especially when harsh vibrations and shocks are existed. The continuous self-test is very important for realising fail-safe system performance according to industry standards. An industrial gyro was also built from the same basic Coriolis-type design.

The structure beams are similar with others, but they go through a cleaner process with extra inspection of the wire bonds in the package. The service life can be 50 years; therefore, it is hardly be fragile in automotive applications. There are four gyros on the same silicon, so the linear acceleration can be eliminated to such a high degree. By trimming during production, the four resonant frequencies are matched at close to 14kHz. The on-chip temperature sensor makes the compensation across -40 to 125°C possible.

With the self test feature, the extra force can be used to the moving masses. The input force can not be seen by the users, because it is at the frequency of 500Hz, except for a flag if something goes wrong. Vibration rectification is only 0.0002°/s/(gravity)2, noise-rate density is 0.02°/sec/√Hz at 105°C, and null offset variation is 3°/s maximum over temperature and product life. Power consumption is 6mA generally.

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