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22 MEMS and Microstructures in Aerospace Applications

FIGURE 2.7 NMP ST6 ISC MEMS 3-axis gyro assembly. (Source: Charles Stark Draper
Laboratory.)

circuit (ASIC) electronics designs. Inertial systems fabricated from similar MEMS
gyro components have been used in precision-guided munitions (PGMs), autono-
mous vehicles, and other space-related mission applications. The silicon MEMS
gyros sense angular rate by detecting the Coriolis effect on a sense mass that is
driven into oscillation by electrostatic motors. Coriolis forces proportioned to the
rotational rate of the body cause the sense mass to oscillate out of plane. This
change is measured by capacitive plates. A more detailed discussion of MEMS
inertial sensors, both gyros and accelerometers, is presented in Chapter 10 of this
book.
The ISC technology, enabled by embedded MEMS gyroscopes, is a precursor of
things to come in the spacecraft avionics arena as the push toward much more
highly integrated, GN&C systems grows in the future. There is a wide range of
science and exploration mission applications that would benefit from the infusion
of the compact, low-power ISC technology. Some envisioned applications
include using the ISC as a ‘‘single sensor’’ solution for attitude determination on
medium-performance spacecraft, as a ‘‘Bolt On’’ — independent safehold sensor
for any spacecraft, or as an acquisition sensor for rendezvous applications. It
has been estimated that approximately 1.5 kg of mass and 26 W of power can
be saved by employing a single MEMS-based attitude sensor such as the ISC
to replace the separate and distinct star tracker and inertial reference units
typically used on spacecraft. 10 So in this case, MEMS is an enhancing technology

© 2006 by Taylor & Francis Group, LLC