Vibrating structure gyroscope

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In science, a vibrating structure gyroscope is a type of gyroscope that functions much like the halteres of insects. Miniaturized devices on this principle can be used as a relatively inexpensive type of Attitude indicator.

The physical principle is very simple: a vibrating object tends to keep vibrating in the same plane as its support is rotated. It is therefore much simpler and cheaper than is a conventional rotating gyroscope of similar accuracy.

In the engineering literature, this type of device is also known as a Coriolis vibratory gyro because as the plane of oscillation is rotated, the response detected by the transducer results from the coriolis term in its equations of motion ("Coriolis force").

Contents 1 Implementations 1.1 Piezoelectric gyroscope 1.2 Wine glass resonator 1.3 Tuning fork gyroscope 1.4 Vibrating wheel gyroscope 1.5 MEMS gyroscope 2 Applications 2.1 Spacecraft orientation 2.2 Automotive 2.3 Other 3 References 4 External links

Implementations

Piezoelectric gyroscope

A piezoelectric crystal can be induced to vibrate, and lateral motion due to coriolis force can be measured to produce a signal related to the rate of rotation Template:Ref.

Wine glass resonator

Also called a hemispherical resonant gyro. Hemisphere driven to resonance and nodal points measured to indicate rotation.

Tuning fork gyroscope

A pair of test masses are driven to resonate and their displacement from the plane of oscillation is measured to produce a signal related to the rate of rotation.

Vibrating wheel gyroscope

A wheel is driven to rotate a fraction of a full turn about its axis. Tilt of the wheel is measured to produce a signal related to the rate of rotation.

MEMS gyroscope

Relatively inexpensive (around US$30 per part in quantity as of early 2006) vibrating structure gyroscopes using MEMS technology are available. These can be implemented as the tuning fork resonator, vibrating wheel or (planar) wine glass resonator Template:Ref.

Applications

Spacecraft orientation

The oscillation can also be induced and controlled in the vibrating structure gyroscope for the positionning of spacecrafts such as Cassini-Huygens. Theses small Hemispherical Resonator Gyroscopes made of quartz operate in vacuum. They provide accurate 3 axis positioning of the spacecraft and are highly reliable over the years as they don't have any moving parts.

Automotive

Automotive roll sensors can be built around vibrating structure gyroscopes. These can be used to detect rollovers, or to supply input to electronic stability control systems.

Other

The Segway Human Transporter employs a vibrating structure gyroscope made by Silicon Sensing Systems to maintain stability of the operator platform Template:Ref.

References

1. Template:NoteNEC ceramic piezo gyros includes animated illustration
2. Template:NoteWhite paper - "A Critical Review of MEMS Gyroscopes Technology and Commercialization Status" Steven Nasiri, Invensense, ca. 2005
3. Template:Note ibid

External links

• New iMEMS® Angular-Rate-Sensing Gyroscope John Geen, Analog Devices
• Silicon Sensing - Case Study: Segway HT