2012

Shahadat Hussain Parvez

Jubair Hossain

Tahmid Hassan Talukdar

12-Apr-12

RC CAR

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Acknowledgement

We are very happy that we have completed our first project on micro controller. This is our best

chance to thank all the people around us who helped us in all the way in this project and on

other project.

We would like to thank our advisor MD Nazmus Sahadat, lecturer, Department of

Electrical and Electronic Engineering, Shahjalal University of Science and Technology, Sylhet,

Whose advises helped us all the way from beginning to end of the project.

At last but not least, we would like to thank our parents without whose support we would been

a big zero

10th April 12, 2012 Shahadat Hussain Parvez

Sylhet Jubair Hossain

Tahmid Hassan Talukdar

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Contents Acknowledgement................................................................................................................................... 2

Introduction: ........................................................................................................................................... 4

Specification: ........................................................................................................................................... 4

Working mechanism (Flow of work) ........................................................................................................ 5

Mechanical Design: ................................................................................................................................. 7

Electrical design:...................................................................................................................................... 8

Schematics: ........................................................................................................................................... 10

Usability: ............................................................................................................................................... 12

Further Possible Upgrades ..................................................................................................................... 13

Photos ................................................................................................................................................... 14

Source codes ......................................................................................................................................... 17

Soft wares and materials used ............................................................................................................... 22

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Introduction: A common idea in human brain is to create some automation. The one and only reason for this

automation is to reduce the efforts needed to do any work. This is the reason for creation of

engineering. All the engineers tries to create automation robots. And the most important part

of robotics is the logic. Creation of robot needs creation of logic. This Remote control car is

anaproach to introduction to robotics.

The idea of this RC Car came as an introduction to robotics. No other project can be better

option other than this to introduce us to vast world of robotics.

Specification:

Body Frame : Aluminum rail

Dimension (Frame) : 7inches* 6Inches

Dimension (With wheel): 7 inches* 8Inches

Weight : 2.5 Kg aprox

Operation mode : Wireless control

Wireless range : 200 m

Movement : 360 degree in any direction (Forward and Backward)

Power : 12 V for Car

9 V for Remote controller

Special security feature : The car automatically stops if it goes out of range of RF.

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Working mechanism (Flow of work)

Description:

The basic mechanism for the movement of the RC car is very simple. You hit forward button

then the car moves forward and if you hit back it moves back. During movement if you hit left

or right the car turns in the respective direction. (For details of the moving see Mechanical

design section) When you hit the any button logic from that button is send to the

microcontroller. This logic data is the processed (Encoded ) in the microcontroller to make it

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ready for sending it to RF transmitter. The RF transmitter then sends some packet data address

through radio waves.

The transmitted radio waves are then received by the Receiver (RX module) which then

sends the received data addresses to another microcontroller. This microcontroller again

processes (decodes) the datas to give some logic output. This logic output is used by the motor

controller circuit to Drive the motors in desired way. (For details of the motor control see

electrical design section)

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Mechanical Design: The mechanical part of the RC car is made with a use of very simple physical law, moment.

Simply if F1 and F2 is same in magnitude then the body will move forward . If F1 is larger than

F2 body turns right and if F2 larger than F1 body turns left. We used this simple moment

physics to design our car.

In the design of the car there are two motors at back side which are the main movement

controller of the car and the front wheel is simply to give support to the movement.

If any motor is rotating then there is a force acting so there is a moment in that

direction. We used this fact to design our car.

If both the motors move forward then the car simply moves forward. If only right motor moves

forward then the car turns left. If the left motor rotates forward then the car turns right. If left

motor rotates reverse the car turns left in reverse direction. If right motor rotates reverse the

car turns right in reverse direction. And if both the motor rotates reverse car moves backward.

If we show the movement logic in table it looks like this:-

Left Motor Right Motor Output

Forward Forward Car moves forward

Forward Stop Car turns right

Stop Forward Car turns left

Reverse Stop Car turns left in reverse gear

Stop Reverse Car turns right in Reverse gear

Reverse Reverse Car move backward

Stop Stop Car at rest

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Electrical design: The main part of the motor control mechanism is the use of L298 IC, which is actually full bridge

driver. Block diagram of internal circuit of L298 is as follows

using one L298 we can control both the motor movement in forward and reverse mode. If IN1

is enabled then left motor rotates forward (Actual connection of motors are as in the figure). If

IN2 is enabled, Left motor rotates in reverse. IN3 makes right motor move forward and IN4

makes right motor back.

A big challenge in rotating motor from the output of L298 is, motor is an inductive load so when

motor is connected the lines acts as short so the motor does not rotates. The solution to this

problem is use if diode bridge in the output as in the figure

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Another challenge in the motor controlling circuit is L298 is bjt based ie it is a current driven IC

and Microcontroller in voltage driven device. So there is a chance of breakdown of

Microcontroller using L298 directly. So to overcome this challenge we used a buffer in between

the output of microcontroller and input of L298

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Schematics: Transmitting End

The above schematics shows the basic circuit used in the transmission of datas from the remote

control to RF waves which is used by the receiver to proceed the process.

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Receiving End

The above schematic shows the receiving end of the movement process. This is where the datas

are processed and made the car move.

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Usability: This car is small in size but usability of this car is very large. It can be used in many ways some of

the common way of using it is described below.

For security reason we can use this car. We can send this car to different places where human

access may be risky. We can send these Cars to different places to gather different information

so that we can ensure safe going of human to those places.

We can use this car for handling things carefully ie to handle glass instruments.

And finally, yes it can be used for entertainment purpose. This car can be used for miniature car

racing in home tracks i.e. in small open place. The driving skills necessary to drive this car is very

less. So the racing game with this can is enjoyable to both children and adults. So this car can be

medium to bring parents children together.

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Further Possible Upgrades

The car can be moderated and upgraded with a video transmission system. If video

transmission is added to this car, then this car can be send to difficult places where human

access is not only risky but quite impossible. We can use this small car for searching purpose.

If mine detectors are added to this system with video transmission then we can use this car for

land mine detections. As we know land mines have a minimum weight (5 kg1) requirement to

blast. And the weight of our car is less compared to minimum trigger requirement so we can

use this can easily to detect mines without exploding it.

Giving this car some automation logic can help us make this car a waiter system in restaurant .

1 Reference : http://www.fourmilab.ch/minerats/hackers96/sld004.html

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Photos

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Source codes Send

#include <avr/io.h> #include <util/delay.h> #ifndef F_CPU #define F_CPU 8000000 #endif #define BAUDRATE 1200 #define UBRRVAL ((F_CPU/(BAUDRATE*16UL))-1) #define ADDRESS 21 void USART_Init(void) // Init Function { UBRRL=(uint8_t)UBRRVAL; UBRRH=(UBRRVAL>>8); UCSRC=(1<<URSEL)|(0<<UMSEL)|(0<<UPM1)|(0<<UPM0)|(0<<USBS)|(0<<UCSZ2)|(1<<UCSZ1)|(1<<UCSZ0); UCSRB=(1<<TXEN); } void USART_vSendByte(uint8_t DATA) // Data Send Function { while((UCSRA&(1<<UDRE)) == 0); UDR = DATA; } void Send_Packet(uint8_t address, uint8_t command) // Packet Send { USART_vSendByte(address); USART_vSendByte(command); USART_vSendByte((address+command)); } int main(void) // Main Function { DDRB = 0x00; USART_Init(); while(1) { while(PINB) {

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while (PINB == 0b10000000) { Send_Packet(ADDRESS, 1); _delay_ms(100); } while (PINB == 0b01000000) { Send_Packet(ADDRESS, 2); _delay_ms(100); } while (PINB == 0b10100000) { Send_Packet(ADDRESS, 3); _delay_ms(100); } while (PINB == 0b10010000) { Send_Packet(ADDRESS, 4); _delay_ms(100); } while (PINB == 0b01100000) { Send_Packet(ADDRESS, 5); _delay_ms(100); } while (PINB == 0b01010000) { Send_Packet(ADDRESS, 6); _delay_ms(100); } while (PINB == 0b00000010) { Send_Packet(ADDRESS, 7); _delay_ms(100); } //else { continue; } } } return 0; }

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Receive #include <avr/io.h> #include <avr/interrupt.h> #include <util/delay.h> #ifndef F_CPU #define F_CPU 8000000 #endif #define BAUDRATE 1200 #define UBRRVAL ((F_CPU/(BAUDRATE*16UL))-1) #define RADDR 21 void USART_Init(void) { UBRRL=(uint8_t)UBRRVAL; UBRRH=(UBRRVAL>>8); UCSRC=(1<<URSEL)|(0<<UMSEL)|(0<<UPM1)|(0<<UPM0)| (0<<USBS)|(0<<UCSZ2)|(1<<UCSZ1)|(1<<UCSZ0); UCSRB=(1<<RXEN)|(1<<RXCIE); //sei(); } uint8_t USART_vReceiveByte(void) { while((UCSRA&(1<<RXC)) == 0); return UDR; } ISR(USART_RXC_vect) { uint8_t raddress, data, chk; raddress=USART_vReceiveByte(); data=USART_vReceiveByte(); chk=USART_vReceiveByte(); while(chk==(raddress+data)) {

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while(raddress==RADDR) { while (data == 1) { PORTD = 0b10100000; break; //_delay_ms(200); } // Forward while (data == 2) { PORTD = 0b01010000; //_delay_ms(200); break; } // Reverse while (data == 3) { PORTD =0b10000000; //_delay_ms(200); break; } // F-R while (data == 4) { PORTD = 0b00100000; //_delay_ms(200); break; } // F-L while (data == 5) { PORTD = 0b01000000; //_delay_ms(200); break; } // R-R while (data == 6) { PORTD = 0b00010000; //_delay_ms(200); break; } // RL /*while (data == 7) { PORTD = 0b00000000; _delay_ms(200); break;

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} // BREAK*/ break; } break; } } int main(void) { DDRD=0b11110000; USART_Init(); while(1) { sei(); _delay_ms(500); PORTD= 0b00000000; } return 0; }

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Soft wares and materials used

Software

Proteus : For Realtime simulation

AVR Studio : For Programming

PonyProg : Program downloading

Hardware

ATmega8 : Microcontroller