Robo India Presents obstacle avoiding robot based on SR-04 Ultrasonic Range finder and Arduino platform.
Buying Links-
You may buy this kit from our store. It is available with original Arduino Board and R-Board
1. http://roboindia.com/store/obstalce-avoiding-robot-uno
2. http://roboindia.com/store/obstalce-avoiding-robot-rb
1. Introduction:
A step by step guide for to make Obstacle avoiding Robot using Robo India’s Motor Shield and Phantom Chassis.
1.2 The motor shield
Robo India offers Arduino compatible Motor shield that can run 2 servo and 2 stepper or 4 DC motor. This shield uses shift register IC. Data is given in serial mode that is converted to parallel by this shift register IC. Connection are as follows.
Board to Shift Register-
- Digital Pin 8 – Data Pin
- Digital Pin 12 – Latch Pin
- Digital Pin 4 – Clock Pin
- Digital Pin 7 – Enable Pin
Shift Register to Motors-
- Q0 – M3 A
- Q1 – M2 A
- Q2 – M1 A
- Q3 – M1 B
- Q4 – M2 B
- Q5 – M4 A
- Q6 – M3 B
- Q7 – M4 B
1.3 Ultrasonic Library:
Here is the library to use this sensor. You may download it from here.
Once you have downloaded this library. Extract this and copy the folder to My Documents/Arduino/Libraries or other similar locations.
2. Assembly and Connections
After assembling the robot make the connection as given in the following diagram. The Power Jumper on the motor shield works as Switch to motor it will be useful while debugging.
2.1 Assembly
Servo Direction-
After assembling the robot will look like –
2.2 Testing motor Connection
It is difficult to find GND and positive supply terminal of motor. Transfer the following code to the Arduino Board. The robot should move in forward direction, if it not doing so, interchange the of the wire of motor. e.g. suppose left motor is rotating in back ward direction and right motor is rotating in forward direction then you have to interchange the wires of M3 terminal.
You may download this sketch from here.
//Robo India Line follower Tutorial
// This codes runs robo int the forward direction.
// Shield Pins Declaration
int dataPin = 8;
int latchPin = 12;
int clockPin = 4;
int en = 7;
void setup()
{
pinMode(dataPin, OUTPUT); // Setting up the motor shield.
pinMode(latchPin, OUTPUT);
pinMode(clockPin, OUTPUT);
pinMode(en, OUTPUT);
digitalWrite(en, LOW);
forward(); // This funtion for forward robot motion
}
void loop()
{
}
void forward(void){
digitalWrite(latchPin, LOW);
shiftOut(dataPin, clockPin, LSBFIRST, 3);
digitalWrite(latchPin, HIGH);
}
void backward(void){
digitalWrite(latchPin, LOW);
shiftOut(dataPin, clockPin, LSBFIRST, 164);
digitalWrite(latchPin, HIGH);
}
void turn_left(void){
digitalWrite(latchPin, LOW);
shiftOut(dataPin, clockPin, LSBFIRST, 161);
digitalWrite(latchPin, HIGH);
}
void turn_right(void){
digitalWrite(latchPin, LOW);
shiftOut(dataPin, clockPin, LSBFIRST, 38);
digitalWrite(latchPin, HIGH);
}
void halt(void){
digitalWrite(latchPin, LOW);
shiftOut(dataPin, clockPin, LSBFIRST, 32);
digitalWrite(latchPin, HIGH);
}
2.3 Programming Obstacle Avoiding Robot
Till the above step you have made all of the connection and your motors are connected to the correct terminals. The following programme is based upon following algorithm.
This is a very basic algorithm for obstacle avoiding robot. We kept this simple so that beginners can understand the concept. You may improve the programme by enhancing algorithm.
It has following predefined function for robot motion-
1. forward() : forward movement of robot.
2. backward() : backward movement of robot.
3. turn_left() : for turning left.
4. turn_right(): for turning right.
5. halt() : for stopping robot.
You may download this sketch from here.
// Tutorial Obstacle avoiding robot
// Prepared by Robo India
// www.roboindia.com
#include <Servo.h> // Includes servo library.
#include <Ultrasonic.h> // Includes SR-04 Sensor Library.
Ultrasonic ultrasonic(A0,A1); // (Trig PIN,Echo PIN)
Servo servo_1; // Creating Servo object.
// declaring Motor Shield
int dataPin = 8;
int latchPin = 12;
int clockPin = 4;
int en = 7;
// Variable to store distance
int left_d = 0;
int right_d = 0;
int front_d = 0;
int max_d = 50; // Max distance to obastacle
void setup()
{
// setting up shield.
pinMode(dataPin, OUTPUT);
pinMode(latchPin, OUTPUT);
pinMode(clockPin, OUTPUT);
pinMode(en, OUTPUT);
digitalWrite(en, LOW);
servo_1.attach(10); // Attaching servo to Pin No.10
servo_1.write(90); // Initial position
delay(350);
}
void loop()
{
front_d = ultrasonic.Ranging(CM); // measuring fornt distance
if (front_d < max_d)
{
halt();
get_d();
if(right_d > max_d)
{
turn_right();
delay(400);
forward();
}
else if ( left_d > max_d)
{
turn_left();
delay(400);
forward();
}
else {
backward();
delay (500);
halt();
}
}
else{
forward();
}
}
void forward(void){ // function for forward movement.
digitalWrite(latchPin, LOW);
shiftOut(dataPin, clockPin, LSBFIRST, 3);
digitalWrite(latchPin, HIGH);
}
void backward(void){ // function for forward movement.
digitalWrite(latchPin, LOW);
shiftOut(dataPin, clockPin, LSBFIRST, 164);
digitalWrite(latchPin, HIGH);
}
void turn_left(void){ // function for left turn.
digitalWrite(latchPin, LOW);
shiftOut(dataPin, clockPin, LSBFIRST, 161);
digitalWrite(latchPin, HIGH);
}
void turn_right(void){ // function for Right turn.
digitalWrite(latchPin, LOW);
shiftOut(dataPin, clockPin, LSBFIRST, 38);
digitalWrite(latchPin, HIGH);
}
void halt(void){ // function for stopping robot.
digitalWrite(latchPin, LOW);
shiftOut(dataPin, clockPin, LSBFIRST, 32);
digitalWrite(latchPin, HIGH);
}
void get_d(void) // Fuction to get distances.
{
servo_1.write(0); // Right Position
delay(500);
right_d = ultrasonic.Ranging(CM);
servo_1.write(90); // Front Positon
delay(500);
front_d = ultrasonic.Ranging(CM);
servo_1.write(180); // Left position of servo
delay(500);
left_d = ultrasonic.Ranging(CM);
servo_1.write(90); // back to front
delay(250);
}
3. Resources:
Robo India’s SR-04 Ultrasonic Sensor Tutorial.
Robo India’s Arduino Servo control Tutorial
This motor shield is based on Adafruit Motor Shield. Resources can be found here.
Buying Links- You may buy this kit from our store. It is available with original Arduino Board and R-Board
1. http://roboindia.com/store/obstalce-avoiding-robot-uno
2. http://roboindia.com/store/obstalce-avoiding-robot-rb
If you have any query please write us at info@roboindia.com
our whatsapp helpline: +91 9694011188
Thanks and Regards
Content Development Team
Robo India
http://roboindia.com