Angular Random Walk Estimation of a Time-Domain Switching Micromachined Gyroscope
17AERP04_10
04/01/2017
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Achieving near navigation-grade performance without the need to produce resonators with very high quality factors.
Space and Naval Warfare Systems Center Pacific, San Diego, California
The primary metrics that prohibit the use of microelectromechanical systems (MEMS) gyroscopes for navigation-grade inertial navigation units (IMUs) are angle random walk (ARW), bias instability, and scale factor instability. The need for MEMS gyroscopes is due to their decreased cost, size, weight, and power (CSWaP) constraints compared to current navigation-grade solutions. Note that to avoid confusion, while in a statistical context a random walk describes a particular type of random process, ARW is used herein to quantify the effects of white, or Gaussian, noise processes on the rate estimate of a gyroscope.
The accepted theory about how to mitigate effects associated with thermomechanical noise, and thus lower ARW, quality factors on the order of a million are needed. While resonators with quality factors on the order of a million have been demonstrated in laboratory settings, navigation-grade ARW has only been demonstrated in high-vacuum systems (<10 μTorr) that would be challenging to implement in a portable system. Other means of reducing ARW, such as increasing the amplitude of the drive mode, can be problematic. For electrostatically transduced devices, which is one of the more common methods used with MEMS, large oscillations can introduce nonlinear behavior such as electrostatic softening or pull-in.
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- Citation
- "Angular Random Walk Estimation of a Time-Domain Switching Micromachined Gyroscope," Mobility Engineering, April 1, 2017.