The Line Follower

A Ball Picking Robot Using PIC 16F877A

Actually this project was a group project. Our task was to build a line following ball-picking robot while keeping the budget below 5000 rupees. If you consider the cost for the parts, it wont exceed that limit. But , for testing and rebuilding it would cost more than that.

Details of the track and  capabilities of the robot

• The robot was expected to operate on an MDF board, approximately 7 ft long and 3.5 ft
wide.
• The surface of the board was painted in black, and a white curvy line (about 2” wide)
was drawn against the black surface.
• A tennis ball was placed at one end of the line and there was a hole at the other end.
An obstacle was placed somewhere on the line.
• Robot was  placed on the white line, near the end where the ball was placed. It moved towards the ball, detected it and grabbed it.
• Then it moved along the line towards the hole, avoided the obstacle, detected the hole
and droped the ball into it.
• The robot was fully autonomous .

Following figure give you more details about the track.

Design and Implementation

We have designed a circuit using Proteus. Our first board was not very successful but the second one was very.

circuit diagram

Printed Circuit Board Layout

Power Supply
We separated a used laptop battery cells and used 6 of them for the power supply . The whole robot was powered by these batteries

Sensor Circuit

The purpose of the sensor circuit is to identify the path that should be followed. 8 IR sensors (FGK 125) were used in the sensor panel but at the time of demonstration only 4 sensors were in a working condition. We have used another 8 IR LEDs to increase the IR signal.

  The black colour absorbs the IR and white colour reflects it. So when it identifies higher amount of IR it tends to follow the current path. When the robot senses a lesser degree of IR it deviates from that path to the previous one.

Motor Control Unit

The motors of the wheel are controlled by the on-board motor control unit.

We designed a separate circuit for driving the ball picking unit. It is shown below. All motors are driven by L 293-D Motor driver IC.

The circuit diagram of Motor driver of the ball picking unit

The Printed Circuit Board layour of Motor driver of the ball picking unit

Obstacle Detecting Mechanism
 We have used Sonar sensor to detect the tennis ball and the obstacle. We used a simple switch to detect the whole

Item	Quantity
Pic16F877A	1
180rpm Gear motor with wheel	2
7805 regulator	2
LM324 IC	2
L293 motor driver	2
In4001 diodes	8
50k pre-set	9
Vero board	1
Circuit wire	5m
Castor wheel	2
IR sensor with IR LED	8
IR LED	8
Sonar Sensor	1
Small motor(30/=)	1
1.5 Li Ion Laptop batteries	6

The Final Outcome

At the final demonstration the ball picking unit did not work. But i followed the line smoothly. The reason for the fault of the ball picking unit was the L293 motor driver. It was burned. This is a picture of the cutie. You may feel ugly... :D but she is beautiful for me.