This document defines functions to control a servo motor and DC motors to move a robot forward, backward, left, and right. It uses an ultrasonic sensor to scan the area and detect obstacles, and directs the robot to turn right, back up and turn right, or turn left depending on where the obstacle is detected to avoid collisions. The robot moves forward and calls the scan function in a loop to continually check for obstacles as it moves.

1. long obstacle = 15;
const int pingPin = 11 ;
const int echoPin = 12;
#include <Servo.h>
long angle[5];
Servo myservo; // create servo object to control a servo
// twelve servo objects can be created on most boards
int pos = 0; // variable to store the servo position
int in1 = 6;
int in2 = 7;
int in3 = 9;
int in4 = 10;
void setup() {
// put your setup code here, to run once:
pinMode(in1, OUTPUT);
pinMode(in2, OUTPUT);
pinMode(in3, OUTPUT);
pinMode(in4, OUTPUT);
Serial.begin(9600);
myservo.attach(9); // attaches the servo on pin 9 to the servo object
}
void loop()
{
forward();
scan();
}
void forward()
{
digitalWrite(in1, HIGH);//in1, in2 for left dc motor
digitalWrite(in2, LOW);
digitalWrite(in3, HIGH);//in3, in4 for right dc motor
digitalWrite(in4, LOW );
delay(1000);
}
void right()
{
digitalWrite(in1, HIGH);
digitalWrite(in2, LOW );
digitalWrite(in3, LOW);
digitalWrite(in4, HIGH );
delay(1000);
}
void left()
{
digitalWrite(in1, LOW);
digitalWrite(in2, HIGH);
digitalWrite(in3, HIGH);
digitalWrite(in4, LOW );
delay(1500);
}
void backward()
{
digitalWrite(in1, LOW);
digitalWrite(in2, HIGH);

2. digitalWrite(in3, LOW);
digitalWrite(in4,HIGH );
delay(2000);
}
void scan()
{
int i=0;
for (pos = 0; pos <= 180; pos += 45)
{ // goes from 0 degrees to 180 degrees in
steps of 45 degree
myservo.write(pos); // tell servo to go to position in
variable 'pos'
angle[i]= look();
i++;
delay(500); // waits 15ms for the servo to reach the
position
}
for( i=0; i < 5; i++) // detecting obstacles
{
if(i < 2)
{
if (angle[i] <= obstacle)
right ();
}
if(i == 2)
{
if (angle[i] <= obstacle)
{
backward ();
delay(100);
right();
}
}
if(i>2)
{
if ( angle[i] <= obstacle)
left();
}
}
delay(500);
for (pos = 180; pos >= 0; pos -= 1)
{
myservo.write(pos); // tell servo to go to position in variable
'pos'
delay(30); // waits 15ms for the servo to reach the
position
}
}
long look()
{
long duration, cm;
// The PING))) is triggered by a HIGH pulse of 2 or more microseconds.
// Give a short LOW pulse beforehand to ensure a clean HIGH pulse:

3. pinMode(pingPin, OUTPUT);
digitalWrite(pingPin, LOW);
delayMicroseconds(2);
digitalWrite(pingPin, HIGH);
delayMicroseconds(5);
digitalWrite(pingPin, LOW);
// The same pin is used to read the signal from the PING))): a HIGH
// pulse whose duration is the time (in microseconds) from the sending
// of the ping to the reception of its echo off of an object.
pinMode(echoPin , INPUT);
duration = pulseIn(echoPin , HIGH);
// convert the time into a distance
cm = duration / 29 / 2;
Serial.print(cm);
Serial.print("cm");
Serial.println();
return cm;
}