1. Disc Resonator Gyroscope (DRG)
Jared Satrom
Chris Fruth

2. Goal of the Project
To conduct research and analysis of a novel MEMS gyroscope design
1) Understand the motivation for the new patent from Boeing and Honeywell and others; why higher performance?
2) Identify new features in the novel design(s) and how higher performances are achieved
3) Compare to existing gyroscope designs
4) Analyze Q (quality) factor improvements

3. Disc Resonating Gyro Basics

4. Disc Resonating Gyro Basics
Gyroscope is driven to resonate in-plane
Electrodes sense deflection in outer ring sockets
Electrodes actuate in inner ring sockets
Circuits process the signal and feedback into the system

5. Operation Principle of the DRG

6. Coriolis Effect
Coriolis acceleration (a) occurs if a resonating disc is pterturbed
Depends on velocities on the disc  higher frequencies allow Coriolis acceleration to dominate centrifugal acceleration
Coriolis acceleration is what the electrodes sense through change in capacitance

7. How Does the DRG Work?
DC Source creates an electrostatic force that moves the disc
Proper control of these electrodes can put the system into resonance
Similarly, the sensing electrodes use gap changes to gauge system changes

8. One Ring or Many? One major advantage of this system is its large area
Compared to a single ring gyro, has much more control over actuation and sensing
Single rings require flexible support beams as well

9. Why Cut the Circles?
With full concentric circles, the structure tends to be rigid
By using arcs instead, the structure becomes more flexible, allowing for better accuracy and performance

10. Ideal Gyro High-Q Large S/N ratio Low-cost Small (1 cm3) Reliable
Requiring low power

11. Q-Factor
Quality factor Q is the measure of energy dissipation

12. Issue: Energy Dissipation Mechanisms
Thermoelasticity: Mechanical energy is exchanged for thermal energy that is diffused
Scattering Loss: “Elastic wave” of resonation is scattered due to material defects
Anchor Loss: Elastic waves travel down the support column of the disc and dissipate
Fluid Damping: Less significant, only a problem for low frequency applications

13. Issue: Stiction and Electrode Damage

14. Benefits of this Design
Has large sensing area compared to other gyros
Easy to package
Multiple sensing and driving electrodes can make it easier to operate and read

15. Fabrication

16. Fabrication

17. Advantages Over Other Designs
MEMS gyroscopes desirable because they are lightweight and cheaper to produce
Isolation from vehicle platform is desirable to limit transmission of external disturbances
A design incorporating:
high sensitivity (as in hemispherical resonators)
simple/inexpensive thin planar Si microfabrication (as in a thin ring gyroscope)

18. Motivation for Higher Performance
Scalability of previous gyroscope designs was poor:
mechanical features were hard to perfect at smaller scales
Sensor noise scales less than size
Therefore, smaller yet more precise and accurate gyros are desired
Adequate areas for driving and sensing while remaining compact

19. The Future of MEMS Gyros
Smaller
Cheaper
Not limited to Silicon
Ti  More durable
Nano and Picosatellites
Submarine & Aircraft satellite launches
Image-stabilizing cellphones?

20. Questions?