A vibrating structure gyroscope, defined by the
IEEE
The Institute of Electrical and Electronics Engineers (IEEE) is a 501(c)(3) professional association for electronic engineering and electrical engineering (and associated disciplines) with its corporate office in New York City and its operati ...
as a Coriolis vibratory gyroscope (CVG), is a
gyroscope
A gyroscope (from Ancient Greek γῦρος ''gŷros'', "round" and σκοπέω ''skopéō'', "to look") is a device used for measuring or maintaining orientation and angular velocity. It is a spinning wheel or disc in which the axis of rot ...
that uses a vibrating structure to determine the rate of rotation. A vibrating structure gyroscope functions much like the
halteres
''Halteres'' (; singular ''halter'' or ''haltere'') (from grc, ἁλτῆρες, weights held in the hands to give an impetus in leaping) are a pair of small club-shaped organs on the body of two orders of flying insects that provide info ...
of flies (
insect
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of ...
s in the order
Diptera
Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...
).
The underlying physical principle is that a
vibrating
Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum ...
object tends to continue vibrating in the same plane even if its support rotates. The
Coriolis effect causes the object to exert a force on its support, and by measuring this force the rate of rotation can be determined.
Vibrating structure gyroscopes are simpler and cheaper than conventional
rotating gyroscopes of similar accuracy. Inexpensive vibrating structure gyroscopes manufactured with
MEMS
Microelectromechanical systems (MEMS), also written as micro-electro-mechanical systems (or microelectronic and microelectromechanical systems) and the related micromechatronics and microsystems constitute the technology of microscopic devices, ...
technology are widely used in smartphones, gaming devices, cameras and many other applications.
Theory of operation
Consider two
proof mass
A proof mass or test mass is a known quantity of mass used in a measuring instrument as a reference for the measurement of an unknown quantity.
A mass used to calibrate a weighing scale is sometimes called a ''calibration mass'' or ''calibration w ...
es vibrating in plane (as in the
MEMS
Microelectromechanical systems (MEMS), also written as micro-electro-mechanical systems (or microelectronic and microelectromechanical systems) and the related micromechatronics and microsystems constitute the technology of microscopic devices, ...
gyro) at frequency
. The
Coriolis effect induces an acceleration on the proof masses equal to
, where
is a
velocity
Velocity is the directional speed of an object in motion as an indication of its rate of change in position as observed from a particular frame of reference and as measured by a particular standard of time (e.g. northbound). Velocity is a ...
and
is an
angular rate
In physics, angular frequency "''ω''" (also referred to by the terms angular speed, circular frequency, orbital frequency, radian frequency, and pulsatance) is a scalar measure of rotation rate. It refers to the angular displacement per unit tim ...
of rotation. The in-plane velocity of the proof masses is given by
, if the in-plane position is given by
. The out-of-plane motion
, induced by rotation, is given by:
:
where
:
is a mass of the proof mass,
:
is a
spring constant
In physics, Hooke's law is an empirical law which states that the force () needed to extend or compress a spring by some distance () scales linearly with respect to that distance—that is, where is a constant factor characteristic of t ...
in the out of plane direction,
:
is a magnitude of a rotation vector in the plane of and perpendicular to the driven proof mass motion.
By measuring
, we can thus determine the rate of rotation
.
Implementations
Cylindrical resonator gyroscope (CRG)
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 piezo-ceramic variants by Watson Industries. A recently patented variant by Innalabs uses a cylindrical design resonator made from
Elinvar
Elinvar is a nickel–iron–chromium alloy notable for having a modulus of elasticity which does not change much with temperature changes. The name is a contraction of the French ('invariable elasticity'). It was invented by Charles Édouard Guil ...
-type alloy with piezoceramic elements for excitation and pickoff at its bottom.
This breakthrough technology gave a substantially increased product life (MTBF > 500,000 hours); with its shock resistance (>300G), it should qualify for "tactical" (mid-accuracy) applications.
The resonator is operated in its second-order resonant mode. The Q-factor is usually about 20,000; that pre-determines its noise and angular random walks. Standing waves are elliptically-shaped oscillations with four antinodes and four nodes located circumferentially along the rim.
The angle between two adjacent antinode – nodes is 45 degrees. One of the elliptical resonant modes is excited to a prescribed amplitude. When the device rotates about its sensitive axis (along its inner stem), the resulting Coriolis forces acting on the resonator's vibrating mass elements excite the second resonant mode. The angle between major axes of the two modes is also 45 degrees.
A closed loop drives the second resonant mode to zero, and the force required to null this mode is proportional to the input rotation rate. This control loop is designated the force-rebalanced mode.
Piezo-electric elements on the resonator produce forces and sense induced motions. This electromechanical system provides the low output noise and large dynamic range that demanding applications require, but suffers from intense acoustic noises and high overloads.
Piezoelectric gyroscopes
A
piezoelectric
Piezoelectricity (, ) is the electric charge that accumulates in certain solid materials—such as crystals, certain ceramics, and biological matter such as bone, DNA, and various proteins—in response to applied mechanical stress. The word ...
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.
Tuning fork gyroscope
This type of gyroscope uses a pair of test masses driven to resonance. Their displacement from the plane of oscillation is measured to produce a signal related to the system's rate of rotation.
F.W. Meredith registered a patent for such a device in 1942 while working at the
Royal Aircraft Establishment
The Royal Aircraft Establishment (RAE) was a British research establishment, known by several different names during its history, that eventually came under the aegis of the UK Ministry of Defence (MoD), before finally losing its identity in mer ...
. Further development was carried out at the RAE in 1958 by G.H. Hunt and A.E.W. Hobbs, who demonstrated drift of less than 1°/h or (2.78)°/s.
Modern variants of tactical gyros use doubled
tuning fork
A tuning fork is an acoustic resonator in the form of a two-pronged fork with the prongs ( tines) formed from a U-shaped bar of elastic metal (usually steel). It resonates at a specific constant pitch when set vibrating by striking it against ...
s such as those produced by American manufacturer Systron Donner in California and French manufacturer
Safran Electronics & Defense
Safran Electronics & Defense, formerly known as Sagem Défense Sécurité, is a French company specializing in optronics, avionics and electronic systems, as well as software for civil and military applications in the naval, aeronautical and space ...
/
Safran
Safran S.A. is a French multinational company that designs, develops and manufactures aircraft engines, rocket engines as well as various aerospace and defense-related equipment or their components. It was formed by a merger between SNECMA and ...
Group.
Wine-glass resonator
Also called a
hemispherical resonator gyroscope
The Hemispherical Resonator Gyroscope (HRG), also called wine-glass gyroscope or mushroom gyro, is a compact, low-noise, high-performance angular rate or rotation sensor. An HRG is made using a thin solid-state hemispherical shell, anchored by a ...
or HRG, a wine-glass resonator uses a thin solid-state hemisphere anchored by a thick stem. The hemisphere with its stem is driven to flexural resonance and the nodal points are measured to detect rotation. There are two basic variants of such a system: one based on a rate regime of operation ("force-to-rebalance mode") and another variant based on an integrating regime of operation ("whole-angle mode"). Usually, the latter one is used in combination with a controlled parametric excitation. It is possible to use both regimes with the same hardware, which is a feature unique to these gyroscopes.
For a single-piece design (i.e., the hemispherical cup and stem(s) form a monolithic part) made from high-purity
quartz glass
Fused quartz, fused silica or quartz glass is a glass consisting of almost pure silica (silicon dioxide, SiO2) in amorphous (non-crystalline) form. This differs from all other commercial glasses in which other ingredients are added which change ...
, it is possible to reach a
Q-factor
In physics and engineering, the quality factor or ''Q'' factor is a dimensionless parameter that describes how underdamped an oscillator or resonator is. It is defined as the ratio of the initial energy stored in the resonator to the energy lo ...
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. Such resonators have to be fine-tuned by ion-beam micro-erosion of the glass or by laser ablation. Engineers and researchers in several countries have been working on further improvements of these sophisticated state-of-art technologies.
Safran
Safran S.A. is a French multinational company that designs, develops and manufactures aircraft engines, rocket engines as well as various aerospace and defense-related equipment or their components. It was formed by a merger between SNECMA and ...
and
Northrop Grumman
Northrop Grumman Corporation is an American multinational aerospace and defense technology company. With 90,000 employees and an annual revenue in excess of $30 billion, it is one of the world's largest weapons manufacturers and military techn ...
are the major manufacturers of
HRG.
Vibrating wheel gyroscope
A wheel is driven to rotate a fraction of a full turn about its axis. The tilt of the wheel is measured to produce a signal related to the rate of rotation.
MEMS gyroscopes
Inexpensive vibrating structure
microelectromechanical systems
Microelectromechanical systems (MEMS), also written as micro-electro-mechanical systems (or microelectronic and microelectromechanical systems) and the related micromechatronics and microsystems constitute the technology of microscopic devices, ...
(MEMS) gyroscopes have become widely available. These are packaged similarly to other
integrated circuit
An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny M ...
s and may provide either analogue or digital outputs. In many cases, a single part includes gyroscopic sensors for multiple axes. Some parts incorporate multiple gyroscopes and
accelerometers
An accelerometer is a tool that measures proper acceleration. Proper acceleration is the acceleration (the rate of change of velocity) of a body in its own instantaneous rest frame; this is different from coordinate acceleration, which is accele ...
(or multiple-axis gyroscopes and
accelerometers
An accelerometer is a tool that measures proper acceleration. Proper acceleration is the acceleration (the rate of change of velocity) of a body in its own instantaneous rest frame; this is different from coordinate acceleration, which is accele ...
), to achieve output that has
six full degrees of freedom. These units are called
inertial measurement unit
An inertial measurement unit (IMU) is an electronic device that measures and reports a body's specific force, angular rate, and sometimes the orientation of the body, using a combination of accelerometers, gyroscopes, and sometimes magnetometer ...
s, or IMUs.
Panasonic
formerly between 1935 and 2008 and the first incarnation of between 2008 and 2022, is a major Japanese multinational conglomerate corporation, headquartered in Kadoma, Osaka. It was founded by Kōnosuke Matsushita in 1918 as a lightbulb s ...
,
Robert Bosch GmbH
Robert Bosch GmbH (; ), commonly known as Bosch and stylized as BOSCH, is a German multinational engineering and technology company headquartered in Gerlingen, Germany. The company was founded by Robert Bosch in Stuttgart in 1886. Bosch is ...
,
InvenSense,
Seiko Epson
Seiko Epson Corporation, or simply known as Epson, is a Japanese multinational electronics company and one of the world's largest manufacturers of computer printers and information- and imaging-related equipment. Headquartered in Suwa, Nagano ...
,
SensonorHanking Electronics STMicroelectronics
STMicroelectronics N.V. commonly referred as ST or STMicro is a Dutch multinational corporation and technology company of French-Italian origin headquartered in Plan-les-Ouates near Geneva, Switzerland and listed on the French stock market. ST ...
,
Freescale Semiconductor
Freescale Semiconductor, Inc. was an American semiconductor manufacturer. It was created by the divestiture of the Semiconductor Products Sector of Motorola in 2004. Freescale focused their integrated circuit products on the automotive, embed ...
, and
Analog Devices
Analog Devices, Inc. (ADI), also known simply as Analog, is an American multinational semiconductor company specializing in data conversion, signal processing and power management technology, headquartered in Wilmington, Massachusetts.
The co ...
are major manufacturers.
Internally, MEMS gyroscopes use 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).
MEMS gyroscopes are used in automotive roll-over prevention and airbag systems, image stabilization, and have many other potential applications.
Applications of CVG gyroscopes
Automotive
Automotive yaw sensors can be built around vibrating structure gyroscopes. These are used to detect error states in yaw compared to a predicted response when connected as an input to
electronic stability control
Electronic stability control (ESC), also referred to as electronic stability program (ESP) or dynamic stability control (DSC), is a computerized technology that improves a vehicle's stability by detecting and reducing loss of traction ( skiddi ...
systems in conjunction with a steering wheel sensor. 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.
Entertainment
The Nintendo Game Boy Advance game
WarioWare: Twisted! uses a piezoelectric gyroscope to detect rotational movement. The Sony
SIXAXIS
The Sixaxis (trademarked SIXAXIS) is a wireless gamepad produced by Sony for their PlayStation 3 video game console. It was introduced alongside the PlayStation 3 in 2006 and remained the console's official controller until 2008. The Sixaxis was ...
PS3 controller uses a single MEMS gyroscope to measure the sixth axis (yaw). The Nintendo
Wii MotionPlus
The is an expansion device for the Wii Remote, the primary game controller for the Wii. The device allows more complex motion to be interpreted than the Wii Remote can do alone. Both the Wii and its successor, the Wii U, support the Wii MotionP ...
accessory uses multi-axis MEMS gyroscopes provided by
InvenSense to augment the motion sensing capabilities of the
Wii Remote
The Wii Remote, also known colloquially as the Wiimote, is the primary game controller for Nintendo's Wii home video game console. An essential capability of the Wii Remote is its motion sensing capability, which allows the user to interact with ...
.
Most modern
smartphone
A smartphone is a portable computer device that combines mobile telephone and computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and extensive mobile operating systems, which ...
s and gaming devices also feature MEMS gyroscopes.
Hobbies
Vibrating structure gyroscopes are commonly used in
radio-controlled helicopter
A radio-controlled helicopter (also '' RC helicopter'') is model aircraft which is distinct from a RC airplane because of the differences in construction, aerodynamics, and flight training. Several basic designs of RC helicopters exist, of w ...
s to help control the helicopter's tail rotor and in
radio-controlled airplane
A radio-controlled aircraft (often called RC aircraft or RC plane) is a small flying machine that is controlled remotely by an operator on the ground using a hand-held radio transmitter. The transmitter continuously communicates with a receiver ...
s to help keep the attitude steady during flight. They are also used in
multirotor
A multirotor or multicopter is a rotorcraft with more than two lift-generating rotors. An advantage of multirotor aircraft is the simpler rotor mechanics required for flight control. Unlike single- and double-rotor helicopters which use complex ...
flight controllers, since multirotors are inherently aerodynamically unstable and cannot stay airborne without electronic stabilization.
Industrial robotics
Epson Robots
EPSON Robots is the robotics design and manufacturing department of Japanese corporation Seiko Epson, the brand-name watch and computer printer producer.
Epson started the production of robots in 1980. Epson manufactures Cartesian, SCARA and 6-a ...
uses a quartz MEMS gyroscope, called QMEMS, to detect and control vibrations on their robots. This helps the robots position the
robot end effector
In robotics, an end effector is the device at the end of a robotic arm, designed to interact with the environment. The exact nature of this device depends on the application of the robot.
In the strict definition, which originates from serial ro ...
with high precision in high speed and fast-deceleration motion.
Photography
Many
image stabilization
Image stabilization (IS) is a family of techniques that reduce blurring associated with the motion of a camera or other imaging device during exposure.
Generally, it compensates for pan and tilt (angular movement, equivalent to yaw and pi ...
systems on video and still cameras employ vibrating structure gyroscopes.
Spacecraft orientation
The oscillation can also be induced and controlled in the vibrating structure gyroscope for the
positioning of spacecraft such as ''
Cassini–Huygens
''Cassini–Huygens'' ( ), commonly called ''Cassini'', was a space-research mission by NASA, the European Space Agency (ESA), and the Italian Space Agency (ASI) to send a space probe to study the planet Saturn and its system, including its r ...
''. These small
hemispherical resonator gyroscope
The Hemispherical Resonator Gyroscope (HRG), also called wine-glass gyroscope or mushroom gyro, is a compact, low-noise, high-performance angular rate or rotation sensor. An HRG is made using a thin solid-state hemispherical shell, anchored by a ...
s made of quartz glass operate in vacuum. There are also prototypes of elastically decoupled cylindrical resonator gyroscopes (CRG)
[Sarapuloff S. A., Lytvynov L.A., ''et al''. Particularities of Designs and Fabrication Technology of High-Q Sapphire Resonators of CRG-1 Type Solid-State Gyroscopes ''//XIVth International Conference on Integrated Navigation Systems (May 28–30, 2007. St.-Petersburg, RF.). – St.-Petersburg. The State Research Center of Russia – Central Scientific & Research Institute "ElektroPribor". RF. 2007. – P.47-48.''] made from high-purity single-crystalline
sapphire
Sapphire is a precious gemstone, a variety of the mineral corundum, consisting of aluminium oxide () with trace amounts of elements such as iron, titanium, chromium, vanadium, or magnesium. The name sapphire is derived via the Latin "sapphi ...
. The high-purity leuko-sapphire have Q-factor an order of value higher than
quartz glass
Fused quartz, fused silica or quartz glass is a glass consisting of almost pure silica (silicon dioxide, SiO2) in amorphous (non-crystalline) form. This differs from all other commercial glasses in which other ingredients are added which change ...
used for HRG, but this material is hard and has
anisotropy
Anisotropy () is the property of a material which allows it to change or assume different properties in different directions, as opposed to isotropy. It can be defined as a difference, when measured along different axes, in a material's physi ...
. They provide accurate 3 axis positioning of the spacecraft and are highly reliable over the years as they have no moving parts.
Other
The
Segway Human Transporter uses a vibrating structure gyroscope made by
Silicon Sensing Systems to stabilize the operator platform.
References
External links
* Proceedings of Anniversary Workshop on Solid-State Gyroscopy (May 19–21, 2008. Yalta, Ukraine). - Kyiv-Kharkiv. ATS of Ukraine. 2009. - . ''See also the next meetings at'': International Workshops on Solid-State Gyroscop
Silicon Sensing – Case Study: Segway HT* Apostolyuk V.
Theory and Design of Micromechanical Vibratory Gyroscopes* Prandi L., Antonello R., Oboe R., and Biganzoli F. Automatic Mode-Matching in MEMS Vibrating Gyroscopes Using Extremum Seeking Control ''//IEEE Transactions on Industrial Electronics. 2009. Vol.56. - P.3880-3891.''
* Prandi L., Antonello R., Oboe R., Caminada C., and Biganzoli F. Open-Loop Compensation of the Quadrature Error in MEMS Vibrating Gyroscopes ''//Proceedings of 35th Annual Conference of the IEEE Industrial Electronics Society – IECON-2009. 2009.'
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Gyroscopes