2. CONTENTS
1. Introduction
2. Working principle of basic mechanical type gyroscope
3. History
4. Uses of mechanical gyroscope
5. Micro-electro-mechanical system gyroscope
6. Fiber-optic gyroscope
3. INTRODUCTION
A gyroscope is a device for measuring or maintaining orientation, based on
the principles of angular momentum.
Mechanically, a gyroscope is a spinning wheel or disk in which the axle is
free to assume any orientation. The most interesting effect is that gravity-
defying part which is called Precession.
Gyroscopes based on other operating principles also exist, such as the
electronic, microchip-packaged MEMS gyroscope , fiber optic gyroscopes
and the extremely sensitive quantum gyroscope.
It is an emerging field of technology. Applications of gyroscopes include
navigation compass, guided missiles, stabilization of radio controlled
helicopters and unmanned planes, balancing of vehicles and smart sensors
for video game controllers.
5. PRINCIPLE OF WORKING
It works on the principle of conservation of angular momentum.
Newton’s first law of motion states that “a body continues to be in a state
of rest or of uniform motion along a straight line unless an external force
acts upon it”.
A rotating object has angular momentum that tends to rotate the object
continuously. So Once the wheel of a gyroscope starts rotating, it resists
any change in its axis of rotation (due to angular momentum). If we apply
an external force that tries to change it, there is an opposite reaction
(Newton’s 3rd law) that pushes it in the opposite direction.
This force is always tangential (perpendicular), and because this point of
the wheel is rotating, the force tends to balance itself in a circular motion,
which also holds the gyroscope spinning against gravity with a single point
of contact.
8. HISTORY
Essentially, a gyroscope is a self-balancing spinning toy, put to
instrumental use.
It was first used as an instrument in 1743 as a level to locate the horizon in
misty condition.
In 1852,Leon Foucault gave it the modern name when he used it in an
experiment involving rotation of earth. (Greek gyros, circle or rotation)
The first functional gyrocompass was patented in 1904 by German
inventor Hermann Anschütz-Kaempfe.
During World War II, the gyroscope became the prime component for
aircraft and anti-aircraft gun sights.
Now 3-axis MEMS-based gyroscopes are being used in portable
electronic devices such as Apple's current generation of iPad, iPhone and
other electronic devices.
10. GYRO-COMPASS
A gyrocompass :
is a type of non-magnetic compass which
is based on a fast-spinning disc and
rotation of the earth.
uses the effect of gyroscopic precession.
is used for navigation on ships, because
they have two significant advantages over
magnetic compasses:
1. they find true north as determined by
Earth's rotation, which is different from,
and navigationally more useful than,
magnetic north.
2. They are unaffected by ferromagnetic
materials, such as ship's steel hull, which
change the magnetic field.
11. GYRO-COMPASS
Errors :
include streaming error, where rapid changes in course, speed and latitude
cause deviation before the gyro can adjust itself.
12. GYRO-CAR
A gyro-car is a two wheeled automobile in which balance is provided by
one or more gyroscopes. Picture below shows first prototype gyro-car The
Schilovski Gyrocar, commissioned in 1912 by the Russian Count .
13. GYRO-CAR
STABILITY CONTROL :
The stabilization of the vehicle is guaranteed by a set of gyroscopes that
are controlled by a microprocessor.
The microprocessor disposes of a low-pass accelerometer which detects
the resultant of the sum of the gravity acceleration plus the possible lateral
acceleration due to a bend.
If this resultant is not coplanar to the design of the vehicle frame, the
microprocessor activates a gyroscope. In case of a non-stationary
disequilibrium, this may be sufficient.
However, if we have to struggle against a constant thrust as soon as the
first gyroscope has attained point 1 and during its weighting(balancing?),
the microprocessor activates the second gyroscope and then if necessary
the third gyroscope.
14. MEMS-GYROSCOPE
Smart-phones employ a electronic
stripped down version which
essentially works on the same
concepts, but in a slimmer, meaner
packages.
A micro-electromechanical system
(MEMS) is an embedded system that
integrates electronic and mechanical
components at a very small scale.
Picture shows the AGD1 2022
FP6AQ chip found in the iPhone 4 is
a MEMS gyroscope, designed by
STMicroelectronics.
15. MEMS-GYROSCOPE
It comprises of of a plate, called the
“proof mass,” that vibrates (oscillates)
when a drive signal is applied to set of
drive capacitor plates. When a user rotates
the phone, the proof mass gets displaced
in the X, Y, and Z directions. A processor
senses the proof mass’ displacement
through capacitor plates located
underneath the proof mass, as well as
finger capacitors at the edges of the
package. The V654A ASIC die converts
the tiny capacitive signals from the
GK10A MEMS die into a digital signal
which is fed into the iphone 4. Then this
data is used to steer the wheel of the car
in the Game, etc..
16. FIBER-OPTIC GYROSCOPE
A fiber optic gyroscope (FOG)
senses changes in orientation,
thus performing the function of a
mechanical gyroscope. However
its principle of operation is
instead based on the interference
of light which has passed through
a coil of optical fiber which can
be as long as 5 km.
17. FIBER-OPTIC GYROSCOPE
OPERATION
Two beams from a laser are injected into the same fiber but in opposite
directions. Due to the Sagnac effect, the beam travelling against the
rotation experiences a slightly shorter path delay than the other beam. The
resulting differential phase shift is measured through interferometry , thus
translating one component of the angular velocity into a shift of the
interference pattern which is measured photo-metrically
18. FIBER-OPTIC GYROSCOPE
ADVANTAGES
A FOG provides extremely precise rotational rate information, in part
because of its lack of cross-axis sensitivity to vibration, acceleration, and
shock.
Unlike the classic spinning-mass gyroscope, the FOG has no moving parts
and doesn't rely on inertial resistance to movement. Hence, this is perhaps
the most reliable alternative to the mechanical gyroscope.
19. FIBER-OPTIC GYROSCOPE
APPLICATIONS
FOGs are used in the inertial
navigation systems of many guided
missiles.
FOGs can be a navigation aid in
remotely operated vehicles and
autonomous underwater vehicles.
