Vibrating structure gyroscope
Inexpensive vibrating structure gyroscopes manufactured with micro-electromechanical systems (MEMS) technology are widely used in smartphones, gaming devices, cameras and many other applications.
This type of gyroscope was developed by GEC Marconi and Ferranti in the 1980s using metal alloys with attached piezoelectric elements and a single-piece piezoceramic design.
Subsequently, in the 90s, CRGs with magneto-electric excitation and readout were produced by American-based Inertial Engineering, Inc. in California, and piezoceramic variants by Watson Industries.
A recently patented variant by Innalabs uses a cylindrical design resonator made from Elinvar-type alloy with piezoceramic elements for excitation and pickoff at its bottom.
This technology gave a substantially increased product life (MTBF > 500,000 hours); with its shock resistance (>300g), it should qualify for "tactical" (mid-accuracy) applications.
A piezoelectric material 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.
Their displacement from the plane of oscillation is measured to produce a signal related to the system's rate of rotation.
Frederick William Meredith registered a patent for such a device in 1942 while working at the Royal Aircraft Establishment.
The hemisphere with its stem is driven to flexural resonance and the nodal points are measured to detect rotation.
For a single-piece design (i.e., the hemispherical cup and stem(s) form a monolithic part) made from high-purity quartz glass, it is possible to reach a Q-factor greater than 30-50 million in vacuum, so the corresponding random walks are extremely low.
The Q is limited by the coating, an extremely thin film of gold or platinum, and by fixture losses.
Panasonic, Robert Bosch GmbH, InvenSense, Seiko Epson, Sensonor, Hanking Electronics, STMicroelectronics, Freescale Semiconductor, and Analog Devices are major manufacturers.
Internally, MEMS gyroscopes use micro-lithographically constructed versions of one or more of the mechanisms outlined above (tuning forks, vibrating wheels, or resonant solids of various designs, i.e., similar to TFG, CRG, or HRG mentioned above).
[10] MEMS gyroscopes are used in automotive roll-over prevention and airbag systems, image stabilization, and have many other potential applications.
These are used to detect error states in yaw compared to a predicted response when connected as an input to electronic stability control systems in conjunction with a steering wheel sensor.
[12] Advanced systems could conceivably offer rollover detection based on a second VSG but it is cheaper to add longitudinal and vertical accelerometers to the existing lateral one to this end.
The Sony SIXAXIS PS3 controller uses a single MEMS gyroscope to measure the sixth axis (yaw).
[14] Many image stabilization systems on video and still cameras employ vibrating structure gyroscopes.
There are also prototypes of elastically decoupled cylindrical resonator gyroscopes (CRG)[16][17] made from high-purity single-crystalline sapphire.
The high-purity leuko-sapphire have Q-factor an order of value higher than quartz glass used for HRG, but this material is hard and has anisotropy.
They provide accurate 3 axis positioning of the spacecraft and are highly reliable over the years as they have no moving parts.
The Segway Human Transporter uses a vibrating structure gyroscope made by Silicon Sensing Systems to stabilize the operator platform.
