SEMINAR PRESENTATION

ON

GYROSCOPE

BY :

LALIT SHARMA

0904028

SUBMITTED IN THE PARTIAL FULFILLMENT OF B.TECH DEGREE:

DEPARTMENT OF MECHANICAL ENGINEERING

DCRUST MURTHAL

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

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.

PRINCIPLE OF WORKING

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.

DEMONSTRATION VIDEO

DIRECTION OF PRECESSION

Gyroscope 3 axes

Spin Torque Precession

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.

USES OF GYROSCOPIC PRINCIPLE

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.

GYRO-COMPASS

Errors : include streaming error, where rapid changes in course, speed and latitude

cause deviation before the gyro can adjust itself.

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 .

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.

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.

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..

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.

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

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.

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.