Electrical And Electronics Design


Line following robots is used been used in industry for years now. They tend to be used in factories and can move from one part of the factory to another by following a line, this line may be painted on the floor or a line of wire overhead. In the course of survey it has been found that the line following robot is a very popular project, which also hold competition throughout the world.


This report will summarize the design, construction and testing of our line following robot. It will show detailed sections on the design stage and how each individual goes about there tasks and finally came together to make the robot function.

The report will also stress the difficulties that we as a group have faced throughout the module as well as the changes that we needed to make to achieve a well-designed line following robot.


The mean aim of this project was to work as a team to design and construct a robot competent of following a black line on a white table.

This project will help to improve our knowledge of robotics as well as electronic circuit design and construction.

Working as a team, and therefore should develop our skills of working together to achieve goals.


Build a Line Following Robot:

  • That will follow a black line path on a white table
  • That will stop if it comes to a break in the line
  • That will have a collision detection system which stops it if an object such as a hand or book is placed in front of the robot.
  • That will be able to pass through a gate 170mm wide and have a maximum length of 180mm.

Project Restrictions

  • Must be made within a budget of 20

Design Schedule

Here is the group Gantt chart, showing when we intended to do the tasks over the year, and when they will be essentially carried out:

Individual Tasks:

Line sensor


Power Supply

Motor control

Obstruction sensors

Line sensor

This is a circuit which is able to see the black line on the table, and convert the vehicles position in relative to the line into a 2 bit digital signal. Where 00 means “off the line”, 01 means “to the left of the line”, 10 means “to the right of the line” and 11 means “on the line”.

Power Supply

This is a circuit which supplies the necessary voltages to all the circuits and systems on the vehicle. The power source will be a 9v battery. The 2 voltage rails initially planned are 9v-to drive the motors, and 5v to drive the low power.


The body will be constructed from plastic. It was designed on SOLIDWORKS a 3D CAD programme and built on an automated rapid prototyping printer.

Motor Control

The motor control circuit controls the speed of each motor therefore steering it around the line. The circuit is built around two NPN transistors.

Obstruction Sensors

The circuit for this task is effectively two circuits, one circuit for the ultrasonic transmitter, and the other circuit is for the ultrasonic receiver.

Sensor Circuit Research and Development

Initial Designs

Research made on the line sensors showed that there are various methods to be used, but in this report I would explain briefly the two main methods

  • A light dependant resistor picking up light reflected off the floor from an LED.
  • A phototransistor picking up light reflected from an infra red LED.

The infra Red option was chosen as the best option over the visual spectrum solution. Firstly that the Infra Red spectrum is a lot cleaner than the visual spectrum, there is a lot less potential for interference. The other advantage is that the phototransistors will react much quicker than the light dependant resistors. However, what appears black and white to the naked eye may not be distinguished in the infrared range.

Chassis Research and Development

Initial Designs of the chassis will be built on software called solid work.

The size of the buggy will be determined by the circuitry which will be going inside it. Since we all have basic idea of the electronics side of the project we will then start to construct the chassis. This determined the positioning of the sensors, motors and the front skid. We decided to position the line follower sensor in such a way to enable it to handle the tightest corners.

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