Introduction
Now day’s many industries are using
robots due to their high level of performance and reliability and which
is a great help for human beings. The obstacle avoidance robotics
is used for detecting obstacles and avoiding the collision. This is an
autonomous robot. The design of obstacle avoidance robot requires the
integration of many sensors according to their task.
The obstacle detection is primary
requirement of this autonomous robot. The robot gets the information
from surrounding area through mounted sensors on the robot. Some sensing
devices used for obstacle detection like bump sensor, infrared sensor,
ultrasonic sensor etc. Ultrasonic sensor is most suitable for obstacle
detection and it is of low cost and has high ranging capability.
Purpose
Designed an autonomous robot which when detects any obstacles in its path, would change direction to avoid collision.
Description
We have designed a simple robot which detects obstacles and
correspondingly changes its direction to avoid collisions. We have used
the mbed controller and interfaced it with an LCD display and 3
Infra-Red sensors. The LCD display indicates the distance of the robot
from the obstacle when the robot is in the range of 80 cm to 10 cm and
it also displays the direction in which the robot will turn when it sees
an obstacle. The 3 infra-red sensors are used to detect obstacles in
the front, right and left direction. The front sensor is the primary
sensor which keeps checking if there are any obstacles in its path in
the front direction. Simultaneously the right and left sensors also keep
checking for obstacles in the right and left direction respectively.
Whenever there is any obstacle detected in the range of 10 centimeters
by the front sensor, the robot will stop and take a turn in either the
right or left direction depending on which side is clear and free from
obstacles. If both the right and left side are free from obstacles, we
have made the robot turn right (One could make it turn left by choice).
When the front sensor and left sensor both detect obstacles within the
range of 10 centimeters, the robot is made to turn right. Similar logic
is used to make the robot left turn. If all the 3 sensors detect
obstacles within the range of 10 centimeters, the robot moves in the
reverse direction.
A robot is a machine that can perform
task automatically or with guidance. Robotics is generally a combination
of computational intelligence and physical machines (motors).
Computational intelligence involves the programmed instructions.
The project proposes robotic vehicle
that has an intelligence built in it such that it guides itself whenever
an obstacle comes ahead of it. This robotic vehicle is built, using a
microcontroller of 8051 family. An ultrasonic sensor is used to detect
any obstacle ahead of it and sends a command to the microcontroller.
Depending on the input signal received,
the microcontroller redirects the robot to move in an alternate
direction by actuating the motors interfaced to it through a motor
driver IC.
This concept in future can be extended
in such a way that if a destination is fed to the robot, the robot can
map the whole terrain and can reach its destination by deciding a
suitable path and avoiding obstacles.
Applications:
1) This line following robot can also be modified to
a walking robot in any surface by using only one motor with homemade
fixtures as per the detailed instructions give.
2) Similarly the same walking robot can be attached with special
magnetic material as per instructions to climb a wall of any vertical
metallic surface say a refrigerator body.
Equipment
- Mbed NXP LPC1768
- Magician Chassis Robot
- Sharp IR sensor GP2Y0A21YK0F
- Dual H-Bridge md08a
- 16x2 LCD Text Display HD44780
Connections
| MBED | Dual H-Bridge Breakout | Robot DC Motors | Battery |
|---|
| MBED | IR-LEFT | IR-CENTRE | IR-RIGHT |
|---|
#include "mbed.h"
#include "motordriver.h"
#include "TextLCD.h"
DigitalOut myled(LED1);
AnalogIn ain1(p20);
AnalogIn ain2(p18);
AnalogIn ain3(p19);
TextLCD lcd(p15, p16, p17, p11, p12, p13);
Motor left(p21, p22, p23, 1);
Motor right(p26, p25, p24, 1);
int main() {
float temp,temp2,temp3;
while (1) {
temp=100*(1- ain1);
if(temp>40){
lcd.printf("distance=%f",temp);
left.speed(0.4);
right.speed(0.4);
wait(0.5);
left.stop(0.5);
right.stop(0.5);
wait(0.005);
temp2=100*(1- ain2);
temp3=100*(1- ain3);
if(temp2<40){
lcd.printf("Take right turn");
left.speed(0.4);
right.stop(1);
wait(0.1);
left.stop(1);
right.stop(1);
wait(0.1);
}
if(temp3<40)
{
lcd.printf("Take left turn");
left.stop(1);
right.speed(0.4);
wait(0.1);
left.stop(1);
right.stop(1);
wait(0.1);
}
if(temp2<40 && temp3<40){
float s;
s=(-1)*(0.5);
lcd.printf("Take reverse turn");
left.speed(s);
right.speed(s);
wait(2);
left.stop(1);
right.stop(1);
wait(0.5);
}
lcd.cls();
}
else
{
temp2=100*(1- ain2);
temp3=100*(1- ain3);
if(temp2<40 && temp3>=40){
lcd.printf("Take right turn");
left.speed(0.4);
right.stop(1);
wait(0.6);
left.stop(1);
right.stop(1);
wait(0.5);
}
if(temp2>=40 && temp3 <40){
lcd.printf("Take left turn");
left.stop(1);
right.speed(0.4);
wait(0.6);
left.stop(1);
right.stop(1);
wait(0.5);
}
if(temp2 >40 && temp3 >40){
lcd.printf("Take right turn by default");
left.speed(0.4);
right.stop(1);
wait(0.6);
left.stop(1);
right.stop(1);
wait(0.5);
}
}
}
}
|
Problems Encountered and Possible Solutions
The robot turns approximately by 90 degrees since we have used the
wait function to make it turn. It could be made to turn to exact 90
degrees by using a compass module. But the problem is that the robot DC
motors have magnets. The magnetic field of these magnets interfere with
the field of the compass and hence the compass gives stray values.
One can try to eliminate this problem by placing the compass as far
as possible by placing the compass on a pole of a reasonably large
height. The compass needs to be at a minimum distance of greater than 5
inches to work properly. Also one needs to take care of the magnetic
fields of the surroundings in order to make the compass work properly.
No comments:
Post a Comment