Minor project

OIST Electronics & Communication

Group members:Aamir HussainAbhikalp GuptaAlind TrivediAnuj KoshtiBhrigu Raj Sharma

Prime Focus-

• Electronic components and circuitry involved• Mechanical aspect• Programming part

Electronic components

Atmega32 microcontrollerCrystal oscillator Resistors capacitorsDiode Drum switches H-bridge

Atmega32 Microcontroller

Key features…

• 8-bit Microcontroller• Up to 1 MIPS Throughput at 16MHz• On-chip Analog Comparator• Operating Voltages

- 4.5-5.5V for ATmega32• Speed Grades

- 0-16 MHz for ATmega32

Utility

• It is being used to operate the two motors• Led’s • The required programming is loaded in the

flash memory, according to which the movement is controlled

Crystal oscillator

Utility

• Operates from 0 to 16 mhz.• Provides the operating frequency for

operation of microcontroller

H-bridge

•Enables a voltage to be applied across a load in either direction.

•These circuits are often used in robotics and other applications to allow DC motors to run forwards and backwards.

H-bridge utility

Circuit of H-bridge

The two basic states of an H bridge

How H-Bridge works

Off Forward Reverse

S1 S2 S3 S4 Result

1 0 0 1Motor

moves right

0 1 1 0Motor

moves left

0 1 0 1Motor brakes

1 0 1 0Motor brakes

The following table summarizes operation, with S1-S4 corresponding to the diagram above.

ACTION OF MOTOR

Others…

• Resistors- for control of current flow• Capacitors- for uninterrupted voltage• FET- for voltage control • Switches • Diodes

Actuators

•Actuators are mechanical devices which converts energy into motion•The energy can be hydraulic, pneumatic or electric.•In order to avoid the complexity we have chosen dc motor as actuator.

Parameters for selecting a motor

• Revolution per minute of shaft (rpm)• Velocity of wheel• Torque• Power• Voltage• Current

RPM of Motor

• rpm of motor is defined as speed of the shaft without any load

• The rpm depends on the load

• The rpm is inversely proportional to torque.

Velocity• It is the rotating speed

of the wheel • Depends on the rpm &

radius of the wheel.V =2*∏*r*ω

• For a constant wheel radius, rpm can be used to control the velocity.

Torque

• Torque α (1 / rotational speed or rpm)

• On increasing the torque rpm will decrease & vice versa

• Having a small load on robot we choose a motor having less torque & more speed

Power• Motor Power = Torque *

rpm• Required power = Force *

velocity• Required power will

depends on – mass of robot – radius of wheel

• To drive robot efficiently:-Motor power > Required

power

Voltage

• DC motors are non polarized i.e. on reversing the polarity the direction of rotation of wheel changes.

• Torque is directly proportional to applied voltage.

Current• The operating current is the

average current drawn by the motor which is required to drive the robot.

• To turn the wheel clockwise or anticlockwise, the direction of current is reversed which is done through H-bridge.

Selection of motor• With all parameters including rpm, velocity, torque,

power, current and voltage required to drive the motor efficiently a geared dc motor of following specifications is selected:

• 100RPM 9V DC with Gearbox• 6mm shaft diameter with internal hole• 125gm weight• 1.2kgcm torque• No-load current = 60 mA(Max), Load current = 300

mA(Max)

What is Differential drive?•The differential drive is a two-wheeled drive system.

• The drive wheels are usually placed on each side of the robot and toward the front

Non driven wheel (metal ball)

Pros:

• Simplicity • Effective for plane surfaces• Cost Effective• Power Efficient

Programming ……………..

For programming software used:oWin AVRoAVR studio 4oPL2303 USB driveroUSB programmer

Why AVR studio 4…………?

AVR Studio 4 includes a debugger that supports

• run control • source and instruction-

level stepping • Registers • I/O views • target configuration and

management

Standard program This program is made on AVR STUDIO 4 in the high level language (user

friendly language) which includes libraries for the compiling and designing of program.

#include <avr/io.h> int main() { Step 1 Set pin2 (PD0) and pin3 (PD1) as output pin; Step 2 Set pin15 (PB1) as output pin; Step 3 Send 0 at PD0 and 1 at PD1; Step 4 Send 1 at PB1; While(1) { //do any job here}Return 0;}

Sample program• This program is for the forward movement of this

programmable moving robot. #include<avr/io.h> #include<util/delay.h> #include<compat/deprecated.h> int main() { DDRC=0b11111111;//data direction register c is initialised by binary value while(1) { sbi(PORTC,1); //sets a bit of portc of ATMEGA32 sbi(PORTC,2); //sets a bit of portc of ATMEGA32 } return(0); }

Thank you

All the glory in the world can be achieved by only……………………….

……………………………beginning…..