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Polar Form Rayleigh Wave Gyroscope

By using Rayleigh waves with a circular wave-front we can improve gyroscope performance whilst simplifying manufacturing.

Background

  • Current MEMS gyroscopes require flexible members in their designs, which are an essential feature for mearing angular rate
    • e.g. ring, cylinder hemispherical and beam based vibratory gyroscopes
  • The design leads to low flexural rigidity and fragile devices
  • This results in inaccuracies in the output of the Gyro (due to drift), or catastrophic failure
  • Under high acceleration (>20,000g) fractures can occur in the gyroscopes rendering them useless
  • Mechanical stops have been used to avoid excessive strain, but this prevents operation of the gyroscope under high acceleration.

Solution

By using Rayleigh waves with a circular wave-front we have been able to isolate the sensing mechanics from the underlying substrate.

This results in:

  • Reduced drift
  • Gyroscopic measurements whilst undergoing acceleration
  • Capable of operating under high g-force (>20,000 g)
  • Simplified manufacturing method

Applications

Depending on substrate selection devices can be made to cater for:

  • Low cost, high volume markets, such as consumer and healthcare applications
  • Performance applications requiring measurements under high g-force.

Image right: Measured (Laser Vibrometry) Polar Form (n=2) Rayleigh Wave (No Reflectors)

Schematics of the gyroscope

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