How a Gimbal Works / Photo Credit: Science - How Stuff Works
WHAT IS A GIMBAL – HISTORY AND APPLICATION (In the Entertainment industry. What
is a Gimbal – History and Application)
What is a Gimbal – History and Application
A gimbal is a pivoted support that allows the rotation of
an object about a single 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 the rotation of its support (e.g.
vertical in the first animation). For example, on a ship, the gyroscopes,
shipboard compasses, stoves, and even drink holders typically use gimbals to
keep them upright with respect to the horizon despite the ship's pitching and
rolling.
The gimbal suspension used for mounting compasses and the
like is sometimes called a Cardan suspension after Italian mathematician and
physicist Gerolamo Cardano (1501–1576) described it in detail. However, Cardano
did not invent the gimbal, nor did he claim to. The device has been known since
antiquity, first described in the 3rd c. BCE by Philo of Byzantium, although
some modern authors support it may not have a single identifiable inventor.
History
The gimbal was first described by the Greek inventor Philo
of Byzantium (280–220 BCE). Philo described an eight-sided ink pot with an
opening on each side, which can be turned so that while any face is on top, a
pen can be dipped and inked — yet the ink never runs out through the holes of
the other sides. This was done by the suspension of the inkwell at the center,
which was mounted on a series of concentric metal rings so that it remained
stationary no matter which way the pot is turned.
In Ancient China, the Han Dynasty (202 BCE – 220 CE)
inventor and mechanical engineer Ding Huan created a gimbal incense burner
around 180 CE. There is a hint in the writing of the earlier Sima Xiangru
(179–117 BCE) that the gimbal existed in China since the 2nd century BCE. There
is mention during the Liang Dynasty (502–557) that gimbals were used for hinges
of doors and windows, while an artisan once presented a portable warming stove
to Empress Wu Zetian (r. 690–705) which employed gimbals. Extant specimens of
Chinese gimbals used for incense burners date to the early Tang Dynasty (618–907),
and were part of the silver-smithing tradition in China.
The authenticity of Philo's description of a cardan
suspension has been doubted by some authors on the ground that the part of
Philo's Pneumatica which describes the use of the gimbal survived only in an
Arabic translation of the early 9th century. Thus, the sinologist Joseph
Needham suspected Arab interpolation as late as 1965. However, Carra de Vaux,
author of the French translation which still provides the basis for modern
scholars, regards the Pneumatics as essentially genuine. The historian of
technology George Sarton (1959) also asserts that it is safe to assume the
Arabic version is a faithful copying of Philo's original, and credits Philon
explicitly with the invention. So does his colleague Michael Lewis (2001). In
fact, research by the latter scholar (1997) demonstrates that the Arab copy
contains sequences of Greek letters which fell out of use after the 1st
century, thereby strengthening the case that it is a faithful copy of the
Hellenistic original, a view recently also shared by the classicist Andrew
Wilson (2002).
The ancient Roman author Athenaeus Mechanicus, writing
during the reign of Augustus (30 BC–14 AD), described the military use of a gimbal-like
mechanism, calling it "little ape" (pithêkion). When preparing to
attack coastal towns from the sea-side, military engineers used to yoke
merchant-ships together to take the siege machines up to the walls. But to
prevent the shipborne machinery from rolling around the deck in heavy seas,
Athenaeus advises that "you must fix the pithêkion on the platform
attached to the merchant-ships in the middle, so that the machine stays upright
in any angle".
After antiquity, gimbals remained widely known in the Near
East. In the Latin West, reference to the device appeared again in the 9th
century recipe book called the Little Key of Painting Mappae clavicula. The
French inventor Villard de Honnecourt depicts a set of gimbals in his famous sketchbook.
In the early modern period, dry compasses were suspended in gimbals.
Applications
In inertial navigation, as applied to ships and
submarines, a minimum of three gimbals are needed to allow an inertial
navigation system (stable table) to remain fixed in inertial space,
compensating for changes in the ship's yaw, pitch, and roll. In this
application, the inertial measurement unit (IMU) is equipped with three
orthogonally mounted gyros to sense rotation about all axes in
three-dimensional space. The gyro outputs are kept to a null through drive
motors on each gimbal axis, to maintain the orientation of the IMU. To
accomplish this, the gyro error signals are passed through
"resolvers" mounted on the three gimbals, roll, pitch and yaw. These
resolvers perform an automatic matrix transformation according to each gimbal
angle, so that the required torques are delivered to the appropriate gimbal
axis. The yaw torques must be resolved by roll and pitch transformations. The
gimbal angle is never measured. Similar sensing platforms are used on aircraft.
In inertial navigation systems, gimbal lock may occur when
vehicle rotation causes two of the three gimbal rings to align with their pivot
axes in a single plane. When this occurs, it is no longer possible to maintain
the sensing platform's orientation.
While
brushless gimbals may not be the right tool for every shot, they are
surprisingly versatile and have the potential to unlock new ways for us tell
stories with more flexibility than ever before.
Rocket
engines
In
spacecraft propulsion, rocket engines are generally mounted on a pair of
gimbals to allow a single engine to vector thrust about both the pitch and yaw
axes; or sometimes just one axis is provided per engine. To control roll, twin
engines with differential pitch or yaw control signals are used to provide
torque about the vehicle's roll axis.
The word
"gimbal" began as a noun. Most modern dictionaries continue to list
it as such. Lacking a convenient term to describe the swinging movement of a
rocket engine, engineers began also using the word "gimbal" as a
verb. When a thrust chamber is swung by an attached actuator, the movement is
referred to as "gimballed" or "gimballing". Official rocket
documentation reflects this usage.
Photography
and imaging
Gimbals are
also used to mount everything from small camera lenses to large photographic
telescopes.
In portable
photography equipment, single-axis gimbal heads are used in order to allow a
balanced movement for camera and lenses. This proves useful in wildlife
photography as well as in any other case where very long and heavy telephoto
lenses are adopted: a gimbal head rotates a lens around its center of gravity,
thus allowing for easy and smooth manipulation while tracking moving subjects.
Very large
gimbal mounts in the form 2 or 3 axis altitude-altitude mounts are used in
satellite photography for tracking purposes.
Gyrostabilized
gimbals which house multiple sensors are also used for airborne surveillance
applications including airborne law enforcement, pipe and power line
inspection, mapping, and ISR (intelligence, surveillance, and reconnaissance).
Sensors include thermal imaging, daylight, low light cameras as well as laser
range finder, and illuminators.
Film and
video
Handheld
3-axis gimbals are used in stabilization systems designed to give the camera
operator the independence of handheld shooting without camera vibration or
shake. Powered by three brushless motors, the gimbals have the ability to keep
the camera level on all axes as the camera operator moves the camera. An
inertial measurement unit (IMU) responds to movement and utilizes its three
separate motors to stabilize the camera.
With the
guidance of algorithms, the stabilizer is able to notice the difference between
deliberate movement such as pans and tracking shots from unwanted shake. This
allows the camera to seem as if it is floating through the air, an effect
achieved by a Steadicam in the past. Gimbals can be mounted to cars and other
vehicles such as drones, where vibrations or other unexpected movements would
make tripods or other camera mounts unacceptable.
Marine
chronometers
The rate of
a mechanical marine chronometer is sensitive to its orientation. Because of
this, chronometers were normally mounted on gimbals, in order to isolate them
from the rocking motions of a ship at sea.
Sources,
References & Credits: Google, Wikipedia, Wikihow, Pinterest, IMDB, Linked
In, Indie Wire, Film Making Stuff, Hiive, Film Daily, New York Film Academy, The
Balance, The Numbers, Film Maker, TV Guide Magazine, Media Match, Quora, Creative
Skill Set, Investopedia, Variety, No Film School, Daily Variety, The Film
Agency, Best Sample Resume, How Stuff Works, Career Trend, Producer's Code of
Credits, Production Hub, Producers Guild of America, Film Connection, Variety, Steadicam,
Tiffen, "3-Axis Handheld GoPro Gimbals". Gimbalreview.com. Gimbal
Review, Dietsch, Roy (2013). Airborne Gimbal Camera – Interface Guide,
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How a Gimbal
Works / Photo Credit: Science - How Stuff Works
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