Saturday, May 9, 2015

Path Following Bot

 





Path follower Bot is another version of a Line Follower Robot. It consists of two major components:


(1) Hardware ( includes the sensors and driving mechanisms ) (2) Software ( path following and grid solving algorithm coded into microcontroller )

Let’s look at the hardware side of the bot : The hardware of the Path follower Bot plays a vital role in functionality of the robot. It should be designed for providing accurate information to the “brain” of the Path follower bot and should be efficient in executing the decisions made by it. The hardware includes:

 

 Sensor 





Sensors used in Path follower bot are Infrared sensors for the purpose of path following and to determine the obstructions in the course. An IR sensor uses the same principle but uses Infrared LEDs instead of ordinary LEDs. Both IR and LDRs can be used for line following, but it would be better to use an IR sensor for determining the obstruction ahead.


Working principle of the IR sensors :



Infrared sensors detect infrared light. The IR light is transformed into an electric current, and this is detected by a voltage or amperage detector. A property of light-emitting diodes (LEDs) is that they produce a certain wavelength of light when an electric current is applied--but they also produce a current when they are subjected to the same wavelength light.

A pair of IR LEDs can be used as motion detectors.

IR sensor is wired in such a way that first IR LED is wired to transmit IR light which is not visible to human eyes. The second LED which is IR detector is basically an IR transistor, due to object ahead IR light from IR LED is reflected back to IR detector, this in turn makes IR transistor to generate a signal. This signal can be amplify depending upon the need.

The signal thereby can be used to drive motor, buzzer, or as an information to microcontroller.



Gear motor

 

 



A geared motor is basically a DC motor coupled with gear box, this is done to get high RPM and Low torque OR low RPM and high torque.

Any geared motor can be used to drive a bot. But one should ensure that the motor is not too fast that the sensors don’t get sufficient time to sense the path’s edges. Direct connection of motor with the microcontroller is not possible. So for ordinary geared motors a motor driving IC L293D must be used. It has got many other functions such as enabling differential drive (mobility in all direction) and pulse width modulation for controlling the speed of motor.



Microcontroller

 

 


Microcontrollers are programmable ICs in which you can store a program in machine code and
execute it. There are many micro controllers but use of either ATmega 16 or ATmega 32 will be
sufficient for solving the path follower or line follower.

ATmega 16 and ATmega 32 are basically same in pin diagram and function except the fact that ATmega 32 has more programmable memory.

ATmega 16 has 4 ports and each port having eight pins. A port is place where you can give your input

(sensors) and tap outputs (motors) depending upon the way they are defined in the program (code)

you load into the micro controller.

There are plenty of AVR board in online stores which are having Atmega16/32 mcu onboard and motor driver IC for driving DC motor and sensor input connection.

These plug n play AVR boards comes with programmer cable as well, through which anyone having programming skill can program these boards and can make such robots on such platform.

Also there are freeduino boards which are easy to program and wired to make line following robot.








Algorithm

 



Some basic and advance line following tutorials can be found here :
Take a look on this video, how the four sensor based path follower robot is actually showing its skills..

 https://www.youtube.com/watch?feature=player_embedded&v=e1k-RzQ4PTI