Automatic Gear Control

AUTOMATIC GEAR CONTROL

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Contents

Introduction
Block Diagram
Components requires
Bibliography

Introduction

today in automobile and mechanical machines we saw automatic gear change and gear technologies. Few machine chnages gear threads with increase in speed. We will make project based on speed and gear rotation. We will use worm ad spur gears.

In this project we measure the speed of motor and when motor speed is change.According to the speed of the motor we change the gear from 1 to 4 automatically. display microcontroller 89s51 interface . in this project we will use stepper motor for gear control. We will use 12v motor. We will ue DC motor also Whose speed When we vary with variable resistance then speed of DC motor will vary. We will use Seven segment display

Microcontroller provide a signal to the motor circuit. Motor is not directly connected with the microcontroller. For the safety of the main processor we interface the motor with optocoupler circuit. Here we use pc 817 ( 4 pin opto coupler) to interface the micro controller with the motor circuit. We use H bridge circuit with the motor. H bridge basically control the movement of the motor. With the help of this H bridge we change the direction of the motor. We use four transistor circuit with each motor. We are using four transistor circuit. Out of these four transistor two transistor is NPN and two transistor and PNP transistor. One NPN and One PNP provide a one direction voltage and motor moves on one direction. Second NPN and second PNP transistor again change the direction of the motor automatically.In this project we will also try to attach Sensors for security purpose. We will use fire sensors-temperature based and LPG sensor. We will also try other sensor.

Block Diagram

WELCOME TO THE WORLD OF THE MICROCONTROLLERS.

Look around. Notice the smart “intelligent” systems? Be it the T.V, washing machines, video games, telephones, automobiles, aero planes, power systems, or any application having a LED or a LCD as a user interface, the control is likely to be in the hands of a micro controller!
Measure and control, that’s where the micro controller is at its best.
Micro controllers are here to stay. Going by the current trend, it is obvious that micro controllers will be playing bigger and bigger roles in the different activities of our lives.
So where does this scenario leave us? Think about it……
The world of Micro controllers
What is the primary difference between a microprocessor and a micro controller? Unlike the microprocessor, the micro controller can be considered to be a true “Computer on a chip”.
In addition to the various features like the ALU, PC, SP and registers found on a microprocessor, the micro controller also incorporates features like the ROM, RAM, Ports, timers, clock circuits, counters, reset functions etc.
While the microprocessor is more a general-purpose device, used for read, write and calculations on data, the micro controller, in addition to the above functions also controls the environment.
We have used a whole lot of technical terms already! Don’t get worried about the meanings at this point. We shall understand these terms as we proceed further

For now just be aware of the fact, that all these terms literally mean what they say.

DC motors

These are the motors that are commonly found in the toys and the tape recorders. These motors change the direction of rotation by changing the polarity. Most chips can't pass enough current or voltage to spin a motor. Also, motors tend to be electrically noisy (spikes) and can slam power back into the control lines when the motor direction or speed is changed.
Specialized circuits (motor drivers) have been developed to supply motors with power and to isolate the other ICs from electrical problems. These circuits can be designed such that they can be completely separate boards, reusable from project to project.
A very popular circuit for driving DC motors (ordinary or gearhead) is called an H-bridge. It's called that because it looks like the capital letter 'H' on classic schematics. The great ability of an H-bridge circuit is that the motor can be driven forward or backward at any speed, optionally using a completely independent power source.

The H-Bridge Circuit

This circuit known as the H-bridge (named for its topological similarity to the letter "H") is commonly used to drive motors. In this circuit two of four transistors are selectively enabled to control current flow through a motor.

opposite pair of transistors (Transistor One and Transistor Three) is enabled, allowing current to flow through the motor. The other pair is disabled, and can be thought of as out of the circuit.

By determining which pair of transistors is enabled, current can be made to flow in either of the two directions through the motor. Because permanent-magnet motors reverse their direction of turn when the current flow is reversed, this circuit allows bidirectional control of the motor.

A gear or cogwheel is a rotatingmachine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque, in most cases with teeth on the one gear being of identical shape, and often also with that shape on the other gear. Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine. Geared devices can change the speed, torque, and direction of a power source. The most common situation is for a gear to mesh with another gear; however, a gear can also mesh with a non-rotating toothed part, called a rack, thereby producing translation instead of rotation.

The gears in a transmission are analogous to the wheels in a crossed belt pulley system. An advantage of gears is that the teeth of a gear prevent slippage.

When two gears mesh, and one gear is bigger than the other (even though the size of the teeth must match), a mechanical advantage is produced, with the rotational speeds and the torques of the two gears differing in an inverse relationship.

In transmissions which offer multiple gear ratios, such as bicycles, motorcycles, and cars, the term gear, as in first gear, refers to a gear ratio rather than an actual physical gear. The term is used to describe similar devices even when the gear ratio is continuous rather than discrete, or when the device does not actually contain any gears, as in a continuously variable transmission.[1]

The earliest known reference to gears was circa A.D. 50 by Hero of Alexandria,[2] but they can be traced back to the Greek mechanics of the Alexandrian school in the 3rd century B.C. and were greatly developed by the Greek polymathArchimedes (287–212 B.C.).[3] The Antikythera mechanism is an example of a very early and intricate geared device, designed to calculate astronomical positions. Its time of construction is now estimated between 150 and 100 BC.[4]

The gears in a transmission are analogous to the wheels in a crossed belt pulley system. An advantage of gears is that the teeth of a gear prevent slippage.

Components required:

MCU 89c2051

Crystal 11.592 MHz- 1 nos.

On/off Switch- 1 nos.

Diodes IN 4001- 10 nos.

Optocoupler 817- 2nos.

Cap 10µf,0.1 µf,330µf

Transistors -547or 548

Resistances 330 Ω,8.2kΩ,30pf

LED

IC7805 voltage Regulator

Motors dc

Infrared sensors set

Copper Clad board

Ply board

Ferric Chloride

Wires

Soldering iron

Soldering wire

Flux

Universal Programmer

Software Required

UMPS

ORCAD

Bibliography

Datashets-