The main task of this robot here is to avoid any sort of obstacle,
which can be done using Infrared waves or the ultrasonic waves. The only
difference between the two, is the sensing range. In this project, we have used
Infrared sensors module, which reflects the infrared waves depending upon the
reflectance characteristic of the object and accordingly senses the accurate
distance. The industries where automated supervision is required, this type of robot is used.
PIC Microcontroller:
The micro-controller used in this project is PIC16f877A, which is a 16f series 40 pin device and has got 33 IO (input/output) pins and the program memory is of 14.3K bytes. The PIC USB ICSP Programmer is used to burn the Hex file of the program from the PC to the RAM memory of the IC. The other details of the PIC 16f877A can be accessed from the data sheet which is attached with this article.
IR Sensors:
Infrared sensors, widely known as IR Sensors, have got one
transmitter and a receiver, where the transmitter transmits the IR waves of the
range 700 nm-1 mm, invisible to human eye and in the presence of an opaque
object, the waves will be reflected back and it will be sensed by a receiver
and hence, the output of the IR sensor will be high. Whereas, in the absence of
an object the waves are transmitted to the infinite region and are not received
by the receiver, hence the output will be low. On the IR sensor module, there
is a LM 358 IC, which is a comparator IC which will compare the threshold
voltage with the output of the IR receiver, the threshold voltage can be
changed by the user by changing the value of the resistance via a
Potentiometer. In this way the sensitivity of the IR Sensor can be changed. The
only limitation of the IR Sensor is it's range, the maximum distance it can
sense can be varied from 10-12 cm and it works on 3.3-5 Volts power supply.
In this project, the IR sensors are placed on the Left,
Center and Right side of the robot, such that it can detect the obstacle on
either of the sides and can respond to it accordingly.
DC Motor:
The DC motor used in this project is a 1000 RPM DC motor,
which is used to facilitate the required forward or reverse motion to avoid the
obstacle. This motor will not run solely on the current provided by the
microcontroller because the current provided by the board is about 20mA and the
DC motor works smoothly only on 500-600mA current, hence, the current amplifier
is used to amplify the current obtained from the board pins. The motor driver
IC used in this project is L293D, which will drive the motor smoothly without
any vibrations or jerks, facilitating smooth motion.
- L293D:
This is an motor driver IC, where the 'D' stands for the
free-wheeling diode, which will not hamper the motor in the absence of any
current, as the motor consists of a coil acting as an inductor hence, the
energy will be dissipated across the diode and hence, it will not damage the
other circuitry. The IC has inbuilt 3 NPN transistors and 1 PNP transistors,
the pair of 1PNP-1NPN transistor makes up the pseudo-darlington pair. 2 motors
can be driven individually from this motor driver IC and the direction as well
as the speed can be controlled via the input and the enable pin. Each motor, is
supplied with the enable pin to make the L293D IC function. Other details of
this IC can be found out on the datasheet, attached with this article.
- Conditions:
Since, 3 IR
sensors are being used there will be
conditions, here n=3 as there are 3 IR
sensors, hence, the conditions will be obeyed as follows:
IR Centre
|
IR Left
|
IR Right
|
Condition
|
0
|
0
|
0
|
Motor
runs in forward direction, moving straight.
|
0
|
0
|
1
|
Motor
runs in forward direction, moving straight.
|
0
|
1
|
0
|
Motor
runs in forward direction, moving straight.
|
0
|
1
|
1
|
Motor
runs in forward direction, moving straight.
|
1
|
0
|
0
|
Motor
reverses it's direction, moves backward, and then right motor stops and the
robot takes a right turn.
|
1
|
0
|
1
|
Motor
reverses it's direction, moves backward, and then left motor stops and the
robot takes a left turn.
|
1
|
1
|
0
|
Motor
reverses it's direction, moves backward, and then right motor stops and the
robot takes a right turn.
|
1
|
1
|
1
|
Both
motor stops.
|
- Robot Model:
figure 1.1: Placement of IR Sensors for detecting obstacle
figure 1.2: Obstacle Avoiding Robot
Demonstration:
1. Here is the video link to the demonstration of the robot : https://youtu.be/OK4ojAxdBIQ
Datasheets:
1. http://akizukidenshi.com/download/PIC16F877A.pdf
2. http://www.ti.com/lit/ds/symlink/l293.pdf
The code will be available to blog followers upon request. :)
hello can I get the codes and circuit diagram
ReplyDeletePLEASE SEND ME THE CODE.
ReplyDeleteYour share is the great knowledge I have gathered, you are an important person I admire, thank you. Visit our website
ReplyDelete