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A gyroscope (from
Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...
γῦρος ''gŷros'', "round" and σκοπέω ''skopéō'', "to look") is a device used for measuring or maintaining
orientation Orientation may refer to: Positioning in physical space * Map orientation, the relationship between directions on a map and compass directions * Orientation (housing), the position of a building with respect to the sun, a concept in building de ...
and
angular velocity In physics, angular velocity or rotational velocity ( or ), also known as angular frequency vector,(UP1) is a pseudovector representation of how fast the angular position or orientation of an object changes with time (i.e. how quickly an objec ...
. It is a spinning wheel or disc in which the axis of rotation (spin axis) is free to assume any orientation by itself. When rotating, the orientation of this axis is unaffected by tilting or rotation of the mounting, according to the
conservation of angular momentum In physics, angular momentum (rarely, moment of momentum or rotational momentum) is the rotational analog of linear momentum. It is an important physical quantity because it is a conserved quantity—the total angular momentum of a closed system ...
. Gyroscopes based on other operating principles also exist, such as the microchip-packaged MEMS gyroscopes found in electronic devices (sometimes called gyrometers), solid-state
ring lasers Ring lasers are composed of two beams of light of the same Polarization (waves), polarization traveling in opposite directions ("counter-rotating") in a closed loop. Ring lasers are used most frequently as gyroscopes (ring laser gyroscope) in mo ...
,
fibre optic gyroscope A fibre-optic gyroscope (FOG) senses changes in orientation using the Sagnac effect, thus performing the function of a mechanical gyroscope. However its principle of operation is instead based on the interference of light which has passed throu ...
s, and the extremely sensitive
quantum gyroscope A quantum gyroscope is a very sensitive device to measure angular rotation based on quantum mechanical principles. The first of these was built by Richard Packard and his colleagues at the University of California, Berkeley. The extreme sensit ...
. Applications of gyroscopes include
inertial navigation system An inertial navigation system (INS) is a navigation device that uses motion sensors (accelerometers), rotation sensors ( gyroscopes) and a computer to continuously calculate by dead reckoning the position, the orientation, and the velocity (dire ...
s, such as in the
Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versa ...
, or inside the steel hull of a submerged submarine. Due to their precision, gyroscopes are also used in
gyrotheodolite In surveying, a gyrotheodolite (also: surveying gyro) is an instrument composed of a gyrocompass mounted to a theodolite. It is used to determine the orientation of true north. It is the main instrument for orientation in mine surveying and in tun ...
s to maintain direction in tunnel mining. Gyroscopes can be used to construct
gyrocompass A gyrocompass is a type of non-magnetic compass which is based on a fast-spinning disc and the rotation of the Earth (or another planetary body if used elsewhere in the universe) to find geographical direction automatically. The use of a gyroc ...
es, which complement or replace magnetic compasses (in ships, aircraft and spacecraft, vehicles in general), to assist in stability (bicycles, motorcycles, and ships) or be used as part of an
inertial guidance system An inertial navigation system (INS) is a navigation device that uses motion sensors (accelerometers), rotation sensors ( gyroscopes) and a computer to continuously calculate by dead reckoning the position, the orientation, and the velocity (dire ...
. MEMS gyroscopes are popular in some consumer electronics, such as smartphones.


Description and diagram

A gyroscope is an instrument, consisting of a wheel mounted into two or three
gimbal A gimbal is a pivoted support that permits rotation of an object about an axis. A set of three gimbals, one mounted on the other with orthogonal pivot axes, may be used to allow an object mounted on the innermost gimbal to remain independent of ...
s providing pivoted supports, for allowing the wheel to rotate about a single axis. A set of three gimbals, one mounted on the other with orthogonal pivot axes, may be used to allow a wheel mounted on the innermost gimbal to have an orientation remaining independent of the orientation, in space, of its support. In the case of a gyroscope with two gimbals, the outer gimbal, which is the gyroscope frame, is mounted so as to pivot about an axis in its own plane determined by the support. This outer gimbal possesses one degree of rotational freedom and its axis possesses none. The second gimbal, inner gimbal, is mounted in the gyroscope frame (outer gimbal) so as to pivot about an axis in its own plane that is always perpendicular to the pivotal axis of the gyroscope frame (outer gimbal). This inner gimbal has two degrees of rotational freedom. The axle of the spinning wheel (the rotor) defines the spin axis. The rotor is constrained to spin about an axis, which is always perpendicular to the axis of the inner gimbal. So the rotor possesses three degrees of rotational freedom and its axis possesses two. The rotor responds to a force applied to the input axis by a reaction force to the output axis. The behavior of a gyroscope can be most easily appreciated by consideration of the front wheel of a bicycle. If the wheel is leaned away from the vertical so that the top of the wheel moves to the left, the forward rim of the wheel also turns to the left. In other words, rotation on one axis of the turning wheel produces rotation of the third axis. A gyroscope flywheel will roll or resist about the output axis depending upon whether the output gimbals are of a free or fixed configuration. An example of some free-output-gimbal devices is the
attitude control Attitude control is the process of controlling the orientation of an aerospace vehicle with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, etc. Controlling vehicle ...
gyroscopes used to sense or measure the pitch, roll and yaw attitude angles in a spacecraft or aircraft. The centre of gravity of the rotor can be in a fixed position. The rotor simultaneously spins about one axis and is capable of oscillating about the two other axes, and it is free to turn in any direction about the fixed point (except for its inherent resistance caused by rotor spin). Some gyroscopes have mechanical equivalents substituted for one or more of the elements. For example, the spinning rotor may be suspended in a fluid, instead of being mounted in gimbals. A
control moment gyroscope A control moment gyroscope (CMG) is an attitude control device generally used in spacecraft attitude control systems. A CMG consists of a spinning rotor and one or more motorized gimbals that tilt the rotor’s angular momentum. As the rotor tilts ...
(CMG) is an example of a fixed-output-gimbal device that is used on spacecraft to hold or maintain a desired attitude angle or pointing direction using the gyroscopic resistance force. In some special cases, the outer gimbal (or its equivalent) may be omitted so that the rotor has only two degrees of freedom. In other cases, the centre of gravity of the rotor may be offset from the axis of oscillation, and thus the centre of gravity of the rotor and the centre of suspension of the rotor may not coincide.


History


Early similar devices

Essentially, a gyroscope is a
top A spinning top, or simply a top, is a toy with a squat body and a sharp point at the bottom, designed to be spun on its vertical axis, balancing on the tip due to the gyroscopic effect. Once set in motion, a top will usually wobble for a few ...
combined with a pair of
gimbal A gimbal is a pivoted support that permits rotation of an object about an axis. A set of three gimbals, one mounted on the other with orthogonal pivot axes, may be used to allow an object mounted on the innermost gimbal to remain independent of ...
s. Tops were invented in many different civilizations, including classical Greece, Rome, and China. Most of these were not utilized as instruments. The first known apparatus similar to a gyroscope (the "Whirling Speculum" or "Serson's Speculum") was invented by
John Serson John Serson (died 1744) was an English sea captain best known for his invention of a " whirling speculum". This was an early form of artificial horizon designed for marine navigation, consisting of a mirror, attached to a spinning top, that attemp ...
in 1743. It was used as a level, to locate the horizon in foggy or misty conditions. The first instrument used more like an actual gyroscope was made by
Johann Bohnenberger Johann Gottlieb Friedrich von Bohnenberger (5 June 1765 – 19 April 1831) was a German astronomer born at Simmozheim, Württemberg. He studied at the University of Tübingen. In 1798, he was appointed professor of mathematics and astro ...
of Germany, who first wrote about it in 1817. At first he called it the "Machine". Bohnenberger's machine was based on a rotating massive sphere. In 1832, American Walter R. Johnson developed a similar device that was based on a rotating disc. The French mathematician
Pierre-Simon Laplace Pierre-Simon, marquis de Laplace (; ; 23 March 1749 – 5 March 1827) was a French scholar and polymath whose work was important to the development of engineering, mathematics, statistics, physics, astronomy, and philosophy. He summarized ...
, working at the
École Polytechnique École may refer to: * an elementary school in the French educational stages normally followed by secondary education establishments (collège and lycée) * École (river), a tributary of the Seine flowing in région Île-de-France * École, Savoi ...
in Paris, recommended the machine for use as a teaching aid, and thus it came to the attention of
Léon Foucault Jean Bernard Léon Foucault (, ; ; 18 September 1819 – 11 February 1868) was a French physicist best known for his demonstration of the Foucault pendulum, a device demonstrating the effect of Earth's rotation. He also made an early measurement ...
.


Foucault gyroscope

In 1852, Foucault used it in an experiment involving the rotation of the Earth. It was Foucault who gave the device its modern name, in an experiment to see (Greek ''skopeein'', to see) the Earth's rotation (Greek ''gyros'', circle or rotation), which was visible in the 8 to 10 minutes before friction slowed the spinning rotor.


Commercialization

In the 1860s, the advent of electric motors made it possible for a gyroscope to spin indefinitely; this led to the first prototype
heading indicator The heading indicator (HI), also known as a directional gyro (DG) or direction indicator (DI), is a flight instrument used in an aircraft to inform the pilot of the aircraft's heading. Use The primary means of establishing the heading in ...
s, and a rather more complicated device, the
gyrocompass A gyrocompass is a type of non-magnetic compass which is based on a fast-spinning disc and the rotation of the Earth (or another planetary body if used elsewhere in the universe) to find geographical direction automatically. The use of a gyroc ...
. The first functional gyrocompass was patented in 1904 by German inventor
Hermann Anschütz-Kaempfe Hermann Franz Joseph Hubertus Maria Anschütz-Kaempfe (3 October 1872 – 6 May 1931) was a German art historian and inventor. He was born in Zweibrücken and died in Munich. In his quest to navigate to the North Pole by submarine, he becam ...
. American
Elmer Sperry Elmer Ambrose Sperry Sr. (October 12, 1860 – June 16, 1930) was an American inventor and entrepreneur, most famous for construction, two years after Hermann Anschütz-Kaempfe, of the gyrocompass and as founder of the Sperry Gyroscope Company. ...
followed with his own design later that year, and other nations soon realized the military importance of the invention—in an age in which naval prowess was the most significant measure of military power—and created their own gyroscope industries. The
Sperry Gyroscope Company Sperry Corporation was a major American equipment and electronics company whose existence spanned more than seven decades of the 20th century. Sperry ceased to exist in 1986 following a prolonged hostile takeover bid engineered by Burroughs ...
quickly expanded to provide aircraft and naval stabilizers as well, and other gyroscope developers followed suit. In 1917, the Chandler Company of Indianapolis created the "Chandler gyroscope", a toy gyroscope with a pull string and pedestal. Chandler continued to produce the toy until the company was purchased by TEDCO Inc. in 1982. The chandler toy is still produced by TEDCO today. In the first several decades of the 20th century, other inventors attempted (unsuccessfully) to use gyroscopes as the basis for early
black box In science, computing, and engineering, a black box is a system which can be viewed in terms of its inputs and outputs (or transfer characteristics), without any knowledge of its internal workings. Its implementation is "opaque" (black). The te ...
navigational systems by creating a stable platform from which accurate acceleration measurements could be performed (in order to bypass the need for star sightings to calculate position). Similar principles were later employed in the development of
inertial navigation system An inertial navigation system (INS) is a navigation device that uses motion sensors (accelerometers), rotation sensors ( gyroscopes) and a computer to continuously calculate by dead reckoning the position, the orientation, and the velocity (dire ...
s for
ballistic missile A ballistic missile is a type of missile that uses projectile motion to deliver warheads on a target. These weapons are guided only during relatively brief periods—most of the flight is unpowered. Short-range ballistic missiles stay within the ...
s. During World War II, the gyroscope became the prime component for aircraft and anti-aircraft gun sights. After the war, the race to miniaturize gyroscopes for guided missiles and weapons navigation systems resulted in the development and manufacturing of so-called midget gyroscopes that weighed less than and had a diameter of approximately . Some of these miniaturized gyroscopes could reach a speed of 24,000 revolutions per minute in less than 10 seconds. Gyroscopes continue to be an engineering challenge. For example, the axle bearings have to be extremely accurate. A small amount of friction is deliberately introduced to the bearings, since otherwise an accuracy of better than 10^ of an inch (2.5 nm) would be required. Three-axis MEMS-based gyroscopes are also being used in portable electronic devices such as tablets,
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, whic ...
s, and
smartwatch A smartwatch is a wearable computer in the form of a watch; modern smartwatches provide a local touchscreen interface for daily use, while an associated smartphone app provides management and telemetry, such as long-term biomonitoring. While ea ...
es. This adds to the 3-axis acceleration sensing ability available on previous generations of devices. Together these sensors provide 6 component motion sensing; accelerometers for X,Y, and Z movement, and gyroscopes for measuring the extent and rate of rotation in space (roll, pitch and yaw). Some devices additionally incorporate a
magnetometer A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, o ...
to provide absolute angular measurements relative to the Earth's magnetic field. Newer MEMS-based inertial measurement units incorporate up to all nine axes of sensing in a single integrated circuit package, providing inexpensive and widely available motion sensing.


Gyroscopic principles

All spinning objects have gyroscopic properties. The main properties that an object can experience in any gyroscopic motion are rigidity in space and
precession Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In othe ...
.


Rigidity in space

Rigidity in space describes the principle that a gyroscope remains in the fixed position on the plane in which it is spinning, unaffected by the Earth's rotation. For example, a bike wheel. Early forms of gyroscope (not then known by the name) were used to demonstrate the principle.


Precession

A simple case of precession, also known as steady precession, can be described by the following relation to Moment: \sum M_x = -I^2 \sin\theta \cos\theta +I_z\phi' \sin\theta(\phi' \cos\theta + \psi' ) where \phi' represents precession, \psi' is represented by spin, \theta is the nutation angle, and I represents inertia along its respective axis. This relation is only valid with the Moment along the Y and Z axises are equal to 0. The equation can be further reduced noting that the angular velocity along the z-axis is equal to the sum of the Precession and the Spin: \omega_z = \phi' \cos \theta + \psi', Where \omega_z represents the angular velocity along the z axis. \sum M_x = -I^2 \sin \theta \cos \theta + I_z \psi' (\sin\theta)\omega_z or \sum M_x = \psi' \sin \theta (I_z\omega_z-I\psi' \cos \theta) Gyroscopic
precession Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In othe ...
is torque induced. Described as the rate of change of the angular momentum and angular velocity that was produced by the same applied torque. This physical phenomenon results in the seemingly impossible dynamic occurrences. For example, a
spinning top A spinning top, or simply a top, is a toy with a squat body and a sharp point at the bottom, designed to be spun on its vertical axis, balancing on the tip due to the gyroscopic effect. Once set in motion, a top will usually wobble for a few se ...
. This gyroscopic process is taken advantage of in many aerospace circumstances, such as airplanes and helicopters to help guide them into a desired orientation.


Contemporary uses


Steadicam

A
Steadicam Steadicam is a brand of camera stabilizer mounts for Movie camera, motion picture cameras invented by Garrett Brown and introduced in 1975 by Cinema Products Corporation. It was designed to isolate the camera from the camera operator's movement ...
rig was employed during the filming of ''
Return of the Jedi ''Return of the Jedi'' (also known as ''Star Wars: Episode VI – Return of the Jedi'' is a 1983 American epic space opera film directed by Richard Marquand. The screenplay is by Lawrence Kasdan and George Lucas from a story by Lucas, who ...
'', in conjunction with two gyroscopes for extra stabilization, to film the background plates for the
speeder bike Speeder bikes (also known as "jumpspeeders" or "hover bikes") and swoop bikes (or just "swoops") are small, fast transports that use repulsorlift engines in the fictional ''Star Wars'' universe. ''Return of the Jedi'' includes a prominent speeder bi ...
chase. Steadicam inventor
Garrett Brown Garrett Brown (born April 6, 1942) is an American inventor, best known as the creator of the Steadicam. Brown's invention allows camera operators to film while walking without the normal shaking and jostles of a handheld camera. The Steadicam wa ...
operated the shot, walking through a redwood forest, running the camera at one frame per second. When projected at 24 frames per second, it gave the impression of flying through the air at perilous speeds.''Empire of Dreams: The Story of the Star Wars Trilogy'' Star Wars Trilogy Box Set DVD documentary, 004/ref>


Heading indicator

The heading indicator or directional gyro has an axis of rotation that is set horizontally, pointing north. Unlike a magnetic compass, it does not seek north. When being used in an airplane, for example, it will slowly drift away from north and will need to be reoriented periodically, using a magnetic compass as a reference.


Gyrocompass

Unlike a directional gyro or heading indicator, a gyrocompass seeks north. It detects the rotation of the Earth about its axis and seeks the ''true'' north, rather than the ''magnetic'' north. Gyrocompasses usually have built-in damping to prevent overshoot when re-calibrating from sudden movement.


Accelerometer

By determining an object's acceleration and integrating over time, the velocity of the object can be calculated. Integrating again, position can be determined. The simplest accelerometer is a weight that is free to move horizontally, which is attached to a spring and a device to measure the tension in the spring. This can be improved by introducing a counteracting force to push the weight back and to measure the force needed to prevent the weight from moving. A more complicated design consists of a gyroscope with a weight on one of the axes. The device will react to the force generated by the weight when it is accelerated, by integrating that force to produce a velocity.


Variations


Gyrostat

A gyrostat consists of a massive flywheel concealed in a solid casing. Its behaviour on a table, or with various modes of suspension or support, serves to illustrate the curious reversal of the ordinary laws of static equilibrium due to the gyrostatic behaviour of the interior invisible flywheel when rotated rapidly. The first gyrostat was designed by
Lord Kelvin William Thomson, 1st Baron Kelvin, (26 June 182417 December 1907) was a British mathematician, Mathematical physics, mathematical physicist and engineer born in Belfast. Professor of Natural Philosophy (Glasgow), Professor of Natural Philoso ...
to illustrate the more complicated state of motion of a spinning body when free to wander about on a horizontal plane, like a top spun on the pavement, or a bicycle on the road. Kelvin also made use of gyrostats to develop mechanical theories of the elasticity of matter and of the ether. In modern
continuum mechanics Continuum mechanics is a branch of mechanics that deals with the mechanical behavior of materials modeled as a continuous mass rather than as discrete particles. The French mathematician Augustin-Louis Cauchy was the first to formulate such m ...
there is a variety of these models, based on ideas of Lord Kelvin. They represent a specific type of Cosserat theories (suggested for the first time by Eugène Cosserat and François Cosserat), which can be used for description of artificially made smart materials as well as of other complex media. One of them, so-called Kelvin's medium, has the same equations as magnetic insulators near the state of magnetic saturation in the approximation of quasimagnetostatics. In modern times, the gyrostat concept is used in the design of attitude control systems for orbiting spacecraft and satellites. For instance, the Mir space station had three pairs of internally mounted flywheels known as ''gyrodynes'' or ''control moment gyros''. In physics, there are several systems whose dynamical equations resemble the equations of motion of a gyrostat. Examples include a solid body with a cavity filled with an inviscid, incompressible, homogeneous liquid, the static equilibrium configuration of a stressed elastic rod in elastica theory, the polarization dynamics of a light pulse propagating through a nonlinear medium, the
Lorenz system The Lorenz system is a system of ordinary differential equations first studied by mathematician and meteorologist Edward Lorenz. It is notable for having chaotic solutions for certain parameter values and initial conditions. In particular, the Lo ...
in chaos theory, and the motion of an ion in a
Penning trap A Penning trap is a device for the storage of charged particles using a homogeneous axial magnetic field and an inhomogeneous quadrupole electric field. This kind of trap is particularly well suited to precision measurements of properties of io ...
mass spectrometer.


MEMS gyroscope

A
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) gyroscope is a miniaturized gyroscope found in electronic devices. It takes the idea of the
Foucault pendulum The Foucault pendulum or Foucault's pendulum is a simple device named after French physicist Léon Foucault, conceived as an experiment to demonstrate the Earth's rotation. A long and heavy pendulum suspended from the high roof above a circular a ...
and uses a vibrating element. This kind of gyroscope was first used in military applications but has since been adopted for increasing commercial use.


HRG

The
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 ...
(HRG), also called a wine-glass gyroscope or mushroom gyro, makes use of a thin solid-state hemispherical shell, anchored by a thick stem. This shell is driven to a flexural resonance by electrostatic forces generated by electrodes which are deposited directly onto separate fused-quartz structures that surround the shell. Gyroscopic effect is obtained from the inertial property of the flexural standing waves.


VSG or CVG

A
vibrating structure gyroscope A vibrating structure gyroscope, defined by the IEEE as a Coriolis vibratory gyroscope (CVG), is a gyroscope that uses a vibrating structure to determine the rate of rotation. A vibrating structure gyroscope functions much like the halteres of fl ...
(VSG), also called a Coriolis vibratory gyroscope (CVG), uses a resonator made of different metallic alloys. It takes a position between the low-accuracy, low-cost MEMS gyroscope and the higher-accuracy and higher-cost fiber optic gyroscope. Accuracy parameters are increased by using low-intrinsic damping materials, resonator vacuumization, and digital electronics to reduce temperature dependent drift and instability of control signals. High quality wine-glass resonators are used for precise sensors like HRG.


DTG

A dynamically tuned gyroscope (DTG) is a rotor suspended by a universal joint with flexure pivots. The flexure spring stiffness is independent of spin rate. However, the dynamic inertia (from the gyroscopic reaction effect) from the gimbal provides negative spring stiffness proportional to the square of the spin speed (Howe and Savet, 1964; Lawrence, 1998). Therefore, at a particular speed, called the tuning speed, the two moments cancel each other, freeing the rotor from torque, a necessary condition for an ideal gyroscope.


Ring laser gyroscope

A
ring laser gyroscope A ring laser gyroscope (RLG) consists of a ring laser having two independent counter-propagating resonant modes over the same path; the difference in phase is used to detect rotation. It operates on the principle of the Sagnac effect which shifts ...
relies on the
Sagnac effect The Sagnac effect, also called Sagnac interference, named after French physicist Georges Sagnac, is a phenomenon encountered in interferometry that is elicited by rotation. The Sagnac effect manifests itself in a setup called a ring interferometer ...
to measure rotation by measuring the shifting interference pattern of a beam split into two separate beams which travel around the ring in opposite directions. When the
Boeing 757 The Boeing 757 is an American narrow-body airliner designed and built by Boeing Commercial Airplanes. The then-named 7N7, a twinjet successor for the 727 (a trijet), received its first orders in August 1978. The prototype completed its mai ...
-200 entered service in 1983, it was equipped with the first suitable ring laser gyroscope. This gyroscope took many years to develop, and the experimental models went through many changes before it was deemed ready for production by the engineers and managers of
Honeywell Honeywell International Inc. is an American publicly traded, multinational conglomerate corporation headquartered in Charlotte, North Carolina. It primarily operates in four areas of business: aerospace, building technologies, performance ma ...
and
Boeing The Boeing Company () is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, telecommunications equipment, and missiles worldwide. The company also provides leasing and product ...
. It was an outcome of the competition with mechanical gyroscopes, which kept improving. The reason Honeywell, of all companies, chose to develop the laser gyro was that they were the only one that didn't have a successful line of mechanical gyroscopes, so they wouldn't be competing against themselves. The first problem they had to solve was that with laser gyros rotations below a certain minimum could not be detected at all, due to a problem called "lock-in", whereby the two beams act like coupled oscillators and pull each other's frequencies toward convergence and therefore zero output. The solution was to shake the gyro rapidly so that it never settled into lock-in. Paradoxically, too regular of a dithering motion produced an accumulation of short periods of lock-in when the device was at rest at the extremities of its shaking motion. This was cured by applying a random
white noise In signal processing, white noise is a random signal having equal intensity at different frequencies, giving it a constant power spectral density. The term is used, with this or similar meanings, in many scientific and technical disciplines, ...
to the vibration. The material of the block was also changed from quartz to a new glass ceramic
Cer-Vit Cer-vit is a family of glass-ceramic materials that were invented by Owens Illinois in the mid-1960s. Its principle ingredients are the oxides of lithium, aluminum and silicon. It is melted to form a glass which is then heat treated to nucleate and ...
, made by
Owens Corning Owens Corning is an American company that develops and produces insulation, roofing, and fiberglass composites and related materials and products. It is the world's largest manufacturer of fiberglass composites. It was formed in 1935 as a partn ...
, because of helium leaks.


Fiber optic gyroscope

A
fiber optic gyroscope A fibre-optic gyroscope (FOG) senses changes in orientation using the Sagnac effect, thus performing the function of a mechanical gyroscope. However its principle of operation is instead based on the interference of light which has passed throu ...
also uses the interference of light to detect mechanical rotation. The two-halves of the split beam travel in opposite directions in a coil of
fiber optic An optical fiber, or optical fibre in Commonwealth English, is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a means to ...
cable as long as 5 km. Like the
ring laser gyroscope A ring laser gyroscope (RLG) consists of a ring laser having two independent counter-propagating resonant modes over the same path; the difference in phase is used to detect rotation. It operates on the principle of the Sagnac effect which shifts ...
, it makes use of the
Sagnac effect The Sagnac effect, also called Sagnac interference, named after French physicist Georges Sagnac, is a phenomenon encountered in interferometry that is elicited by rotation. The Sagnac effect manifests itself in a setup called a ring interferometer ...
.


London moment

A
London moment The London moment (after Fritz London) is a quantum-mechanical phenomenon whereby a spinning superconductor generates a magnetic field whose axis lines up exactly with the spin axis. The term may also refer to the magnetic moment of any rotati ...
gyroscope relies on the quantum-mechanical phenomenon, whereby a spinning superconductor generates a
magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...
whose axis lines up exactly with the spin axis of the gyroscopic rotor. A magnetometer determines the orientation of the generated field, which is
interpolated In the mathematical field of numerical analysis, interpolation is a type of estimation, a method of constructing (finding) new data points based on the range of a discrete set of known data points. In engineering and science, one often has a n ...
to determine the axis of rotation. Gyroscopes of this type can be extremely accurate and stable. For example, those used in the
Gravity Probe B Gravity Probe B (GP-B) was a satellite-based experiment to test two unverified predictions of general relativity: the geodetic effect and frame-dragging. This was to be accomplished by measuring, very precisely, tiny changes in the direction of ...
experiment measured changes in gyroscope spin axis orientation to better than 0.5
milliarcseconds A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The n ...
(1.4 degrees, or about ) over a one-year period. This is equivalent to an
angular separation Angular distance \theta (also known as angular separation, apparent distance, or apparent separation) is the angle between the two sightlines, or between two point objects as viewed from an observer. Angular distance appears in mathematics (in pa ...
the width of a human hair viewed from away. The GP-B gyro consists of a nearly-perfect spherical rotating mass made of
fused quartz 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 ...
, which provides a
dielectric In electromagnetism, a dielectric (or dielectric medium) is an electrical insulator that can be polarised by an applied electric field. When a dielectric material is placed in an electric field, electric charges do not flow through the mate ...
support for a thin layer of
niobium Niobium is a chemical element with chemical symbol Nb (formerly columbium, Cb) and atomic number 41. It is a light grey, crystalline, and ductile transition metal. Pure niobium has a Mohs hardness rating similar to pure titanium, and it has sim ...
superconducting material. To eliminate friction found in conventional bearings, the rotor assembly is centered by the electric field from six electrodes. After the initial spin-up by a jet of helium which brings the rotor to 4,000
RPM Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min−1) is a unit of rotational speed or rotational frequency for rotating machines. Standards ISO 80000-3:2019 defines a unit of rotation as the dimensionl ...
, the polished gyroscope housing is evacuated to an ultra-high vacuum to further reduce drag on the rotor. Provided the suspension electronics remain powered, the extreme
rotational symmetry Rotational symmetry, also known as radial symmetry in geometry, is the property a shape has when it looks the same after some rotation by a partial turn. An object's degree of rotational symmetry is the number of distinct orientations in which i ...
, lack of friction, and low drag will allow the angular momentum of the rotor to keep it spinning for about 15,000 years. A sensitive DC SQUID that can discriminate changes as small as one quantum, or about 2 Wb, is used to monitor the gyroscope. A
precession Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In othe ...
, or tilt, in the orientation of the rotor causes the London moment magnetic field to shift relative to the housing. The moving field passes through a superconducting pickup loop fixed to the housing, inducing a small electric current. The current produces a voltage across a shunt resistance, which is resolved to spherical coordinates by a microprocessor. The system is designed to minimize Lorentz torque on the rotor.


Other examples


Helicopters

The main rotor of a helicopter acts like a gyroscope. Its motion is influenced by the principle of gyroscopic precession which is the concept that a force applied to a spinning object will have a maximum reaction approximately 90 degrees later. The reaction may differ from 90 degrees when other stronger forces are in play. To change direction, helicopters must adjust the pitch angle and the angle of attack.


Gyro X

Gyro X prototype vehicle created by Alex Tremulis and Thomas Summers in 1967. The car utilized gyroscopic precession to drive on two wheels. An assembly consisting of a flywheel mounted in a gimbal housing under the hood of the vehicle acted as a large gyroscope. The flywheel was rotated by hydraulic pumps creating a gyroscopic effect on the vehicle. A precessional ram was responsible for rotating the gyroscope to change the direction of the precessional force to counteract any forces causing the vehicle imbalance. The one-of-a-kind prototype is now at the Lane Motor Museum in Nashville, Tennessee.


Consumer electronics

In addition to being used in compasses, aircraft, computer pointing devices, etc., gyroscopes have been introduced into consumer electronics. The first usage or application of the gyroscope in consumer electronics was popularized by
Steve Jobs Steven Paul Jobs (February 24, 1955 – October 5, 2011) was an American entrepreneur, industrial designer, media proprietor, and investor. He was the co-founder, chairman, and CEO of Apple; the chairman and majority shareholder of Pixar; a ...
in the Apple iPhone. Since the gyroscope allows the calculation of orientation and rotation, designers have incorporated them into modern technology. The integration of the gyroscope has allowed for more accurate recognition of movement within a 3D space than the previous lone
accelerometer 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 ...
within a number of smartphones. Gyroscopes in consumer electronics are frequently combined with accelerometers for more robust direction- and motion-sensing. Examples of such applications include smartphones such as the
Samsung Galaxy Note 4 The Samsung Galaxy Note 4 is an Android smartphone developed and produced by Samsung Electronics. It was unveiled during a Samsung press conference at IFA Berlin on 3 September 2014 and was released globally in October 2014 as successor to th ...
,
HTC Titan The HTC Titan (stylized and marketed as uppercase HTC TITAN; also known as the HTC Eternity in China, and HTC Ultimate in Brazil), is a smartphone running the Windows Phone OS 7.5 (codename Mango) operating system. The phone was designed and man ...
,
Nexus 5 Nexus 5 (code-named Hammerhead) is an Android smartphone sold by Google and manufactured by LG Electronics. It is the fifth generation of the Nexus series, succeeding the Nexus 4. It was unveiled on October 31, 2013 and served as the launc ...
,
iPhone 5s The iPhone 5S (stylized and marketed as iPhone 5s) is a smartphone that was designed and marketed by Apple Inc. It is the seventh generation of the iPhone, succeeding the iPhone 5, and unveiled in September 2013, alongside the iPhone 5C. Th ...
,
Nokia 808 PureView The Nokia 808 PureView is a Symbian-powered smartphone first unveiled on 27 February 2012 at the Mobile World Congress. It is the first smartphone to feature Nokia's PureView Pro technology, a pixel oversampling technique that reduces an im ...
and
Sony Xperia Xperia () is the brand name of smartphones and tablets from Sony. The name Xperia is derived from the word "experience", and was first used in the Xperia X1 tagline of "I Xperia the best". Sony Mobile was previously known globally as Sony Er ...
, game console peripherals such as the
PlayStation 3 controller is a video gaming brand that consists of five home video game consoles, two handhelds, a media center, and a smartphone, as well as an online service and multiple magazines. The brand is produced by Sony Interactive Entertainment, a divis ...
and 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 ...
, and virtual reality sets such as the
Oculus Rift Oculus Rift is a discontinued line of virtual reality headsets developed and manufactured by Oculus VR, a division of Meta Platforms, released on March 28, 2016. In 2012 Oculus initiated a Kickstarter campaign to fund the Rift's development, af ...
.
Nintendo is a Japanese Multinational corporation, multinational video game company headquartered in Kyoto, Japan. It develops video games and video game consoles. Nintendo was founded in 1889 as by craftsman Fusajiro Yamauchi and originally produce ...
has integrated a gyroscope into the
Wii The Wii ( ) is a home video game console developed and marketed by Nintendo. It was released on November 19, 2006, in North America and in December 2006 for most other Regional lockout, regions of the world. It is Nintendo's fifth major ho ...
console's Wii Remote controller by an additional piece of hardware called "
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 ...
". It is also included in the 3DS, Wii U GamePad, and
Nintendo Switch The is a hybrid video game console developed by Nintendo and released worldwide in most regions on March 3, 2017. The console itself is a Tablet computer#Gaming tablet, tablet that can either be docking station, docked for use as a home video ...
Joy-Con Joy-Con are the primary game controllers for the Nintendo Switch video game console. They consist of two individual units, each containing an analog stick and an array of buttons. They can be used while attached to the main Nintendo Switch cons ...
controllers, which detect movement when turning and shaking. Cruise ships use gyroscopes to level motion-sensitive devices such as self-leveling pool tables. An electric powered flywheel gyroscope inserted in a bicycle wheel is sold as an alternative to training wheels. Some features of Android phones like PhotoSphere or 360 Camera and to use VR gadget do not work without a gyroscope sensor in the phone.


See also

*
Aerotrim An aerotrim (also known as Multi-Axis Trainer or MAT) is a 3-axis gimbal large enough to contain a human being, used for cardiovascular workout and equilibrioception (balance) training in pilots and astronauts. Aerotrims saw use in gyms during ...
*
Accelerometer 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 ...
*
Anti-rolling gyro Ship stabilizing gyroscopes are a technology developed in the 19th century and early 20th century and used to stabilize roll motions in ocean-going ships. It lost favor in this application to hydrodynamic roll stabilizer fins because of reduced co ...
*
Attitude indicator The attitude indicator (AI), formerly known as the gyro horizon or artificial horizon, is a flight instrument that informs the pilot of the aircraft orientation relative to Earth's horizon, and gives an immediate indication of the smallest o ...
*
Balancing machine A balancing machine is a measuring tool used for balancing rotating machine parts such as rotors for electric motors, fans, turbines, disc brakes, disc drives, propellers and pumps. The machine usually consists of two rigid pedestals, with suspe ...
*
Countersteering Countersteering is used by single-track vehicle operators, such as cyclists and motorcyclists, to initiate a turn toward a given direction by momentarily steering counter to the desired direction ("steer left to turn right"). To negotiate a turn ...
*
Euler angles The Euler angles are three angles introduced by Leonhard Euler to describe the Orientation (geometry), orientation of a rigid body with respect to a fixed coordinate system.Novi Commentarii academiae scientiarum Petropolitanae 20, 1776, pp. 189 ...
*
Eric Laithwaite Eric Roberts Laithwaite (14 June 1921 – 27 November 1997) was a British electrical engineer, known as the "Father of Maglev" for his development of the linear induction motor and maglev rail system. Biography Eric Roberts Laithwaite wa ...
*
Gyrocar A gyrocar is a two-wheeled automobile. The difference between a bicycle or motorcycle and a gyrocar is that in a bike, dynamic balance is provided by the rider, and in some cases by the geometry and mass distribution of the bike itself, and the g ...
*
Gyro monorail The gyro monorail, gyroscopic monorail, gyro-stabilized monorail, or gyrocar are terms for a single rail land vehicle that uses the gyroscopic action of a spinning wheel to overcome the inherent instability of balancing on top of a single rail. ...
*
Gyroscopic exercise tool A gyroscopic exercise tool is a device used to exercise the wrist as part of physical therapy in order to build palm, forearm and finger strength. It can also be used as a unique demonstration of some aspects of rotational dynamics. The devic ...
*
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 ...
*
Magnetometer A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, o ...
*
Molecular gyroscope Molecular gyroscopes are chemical compounds or supramolecular complexes containing a rotor that moves freely relative to a stator, and therefore act as gyroscopes. Though any single bond or triple bond permits a chemical group to freely rotate ...
*
Reaction wheel A reaction wheel (RW) is used primarily by spacecraft for three-axis attitude control, and does not require rockets or external applicators of torque. They provide a high pointing accuracy, and are particularly useful when the spacecraft must be ...
*
Rifling In firearms, rifling is machining helical grooves into the internal (bore) surface of a gun's barrel for the purpose of exerting torque and thus imparting a spin to a projectile around its longitudinal axis during shooting to stabilize the pro ...
*
Rigid body dynamics In the physical science of dynamics, rigid-body dynamics studies the movement of systems of interconnected bodies under the action of external forces. The assumption that the bodies are ''rigid'' (i.e. they do not deform under the action of a ...
*
Turn and bank indicator In aviation, the turn and slip indicator (T/S, a.k.a. turn and bank indicator) and the turn coordinator (TC) variant are essentially two aircraft flight instruments in one device. One indicates the rate of turn, or the rate of change in the aircr ...
*
Turn coordinator In aviation, the turn and slip indicator (T/S, a.k.a. turn and bank indicator) and the turn coordinator (TC) variant are essentially two aircraft flight instruments in one device. One indicates the rate of turn, or the rate of change in the aircr ...
* Stabilizer


Notes


References

*


Further reading

*
Felix Klein Christian Felix Klein (; 25 April 1849 – 22 June 1925) was a German mathematician and mathematics educator, known for his work with group theory, complex analysis, non-Euclidean geometry, and on the associations between geometry and group ...
and
Arnold Sommerfeld Arnold Johannes Wilhelm Sommerfeld, (; 5 December 1868 – 26 April 1951) was a German theoretical physicist who pioneered developments in atomic and quantum physics, and also educated and mentored many students for the new era of theoretica ...
, "''Über die Theorie des Kreisels''" (Tr., About the theory of the gyroscope). Leipzig, Berlin, B.G. Teubner, 1898–1914. 4 v. illus. 25 cm. * Audin, M. ''Spinning Tops: A Course on Integrable Systems''. New York: Cambridge University Press, 1996. * Crabtree, H. "An Elementary Treatment of the Theory of Spinning Tops and Gyroscopic Motion". Longman, Green and C), 1909. Reprinted by Michigan Historical Reprint Series. * Proceedings of Anniversary Workshop on Solid-State Gyroscopy, 19–21 May 2008. Yalta, Ukraine. Kyiv-Kharkiv. ATS of Ukraine, (2009) * E. Leimanis (1965). ''The General Problem of the Motion of Coupled Rigid Bodies about a Fixed Point''. (Springer, New York). * Perry J. "Spinning Tops". London Society for Promoting Christian Knowledge, 1870. Reprinted by Project Gutemberg ebook, 2010. * Walter Wrigley, Walter M. Hollister, and William G. Denhard (1969). ''Gyroscopic Theory, Design, and Instrumentation.'' (MIT Press, Cambridge, MA). * Provatidis, C. G. (2012). Revisiting the Spinning Top, ''International Journal of Materials and Mechanical Engineering'', Vol. 1, No. 4, pp. 71–88, open access a
Ijm-me.org
(ISSN Online: 2164-280X, ISSN Print: 2162-0695). * Cooper, Donald & University of Western Australia. Dept. of Mechanical and Materials Engineering 1996, An investigation of the application of gyroscopic torque in the acceleration and retardation of rotating systems.


External links


The Royal Institution's 1974–75 Christmas Lecture
Professor Eric Laithwaite
One-Wheeled Robot-Gyrostat
by Olga Kapustina and Yuri Martynenko
Wolfram Demonstrations Project The Wolfram Demonstrations Project is an organized, open-source collection of small (or medium-size) interactive programs called Demonstrations, which are meant to visually and interactively represent ideas from a range of fields. It is hos ...
* Apostolyuk V
Theory and Design of Micromechanical Vibratory Gyroscopes
{{Authority control Flywheels 1852 introductions