Line following robot

Line follower is an autonomous robot which follows either black line in white area or white line in black area. Robot must be able to detect particular line and keep following it.For special situations such as cross overs where robot can have more than one path which can be followed, predefined path must be followed by the robot.Line following is a task in which robot has to follow the line. It must be capable of taking various degrees of turns to follow the curved lines also.

To make a basic LFR first we have to design the mechanical part or the body of the robot, then defining the kinematics of the robots and last but not the least designing the control of the robot.



 The mechanical part or body of the robot can be designed using AutoCAD or Workspace. A basic LFR can consist of a base at the two ends of which the wheels are attached. A square or rectangular sheet of hard plastic can be used as the base.The LFR can be a wheeled mobile robot with a fixed base, a legged mobile robot with multiple inflexible bodies interconnected by joints.

Kinematic analysis of the robot includes the description of its motion with respect to a fixed coordinate system. It is concerned mainly with the movement of the robot and with motion of each body in case of a legged robot. The whole path of the robot is set using the Kinematic analysis. We can do this using Workspace software.

the most important aspect of its working is the control of the robot. The term control refers to the robot motion control, i.e. controlling the movement of the wheels. A basic LFR follows certain path and the motion of the robot along this path is controlled by controlling the rotation of wheels, which are placed on the shafts of the two motors. So, the basic control is achieved by controlling the motors. The control circuit includes the use of sensors to sense the path and the microcontroller or any other device to control the motor operation through the motor drivers, depended on the sensor output. there are two ways of controlling a LFR, i.e without using Microcontrollers and using Microcontrollers.

Without using Microcontroller: It consists of an IR-LED and Photodiode arrangement for each motor which is controlled by the switching on and off of the transistor. IR or VISIBLE light is emitted from the emitter. This IR light is reflected in case of a white surface and the reflected IR light is incident on the photodiode. The resistance of the photodiode decreases, which leads to an increase in current through it and that is why the voltage drop across it. The photodiode is connected to the base of the transistor and as a result of increased voltage across the photodiode, the transistor starts conducting and thus the motor connected to the collector of the transistor gets enough supply to start rotating. In case of a black color on the path encountered by one of the sensor arrangement, the IR light is not reflected and the photodiode offers more resistance, causing the transistor to stop conduction and eventually the motor stops rotating. The whole system can be controlled using a simple LED-Photodiode-Transistor arrangement. With using Microcontrollers : The line following robot is one of the self-operating robots. which detects and follows a line drawn on the area. The line is indicated by white line on a block surface or block line on a white surface. This system must be sense by the line. This application is depends upon the sensors. Here we are using two sensors for path detection purpose. That is proximity sensor and IR sensor. The proximity sensor used for path detection and IR sensor used for obstacle detection. These sensors mounted at front end of the robot. The microcontroller is an intelligent device the whole circuit is controlled by the microcontroller. Sensors are required to detect position of the line to be followed with respect to the robot’s position. Most widely used sensors for the line follower robot are PHOTOSENSORS. They are based on the basic observation that “the white surface reflects the light and the black surface absorbs it”.Sensor circuit contains emitter, detector and comparator assembly. These robots can be used as automated equipment carriers in industries replacing traditional conveyer belts.These can also be used at homes for domestic purposes like floor cleaning etc.These can be used in public places like shopping malls, museums etc to provide path guidance.