Hello everyone, I am buliding an obstacle avoiding car but I am facing a big problem in it.
The car just keeps on revolving in circles. It takes too many turns and ultimately moves only in circles. Instead of moving away from the obstacle, it goes towards it. Or, I should say it moves only in a circle. I have used the following code:
#include <AFMotor.h> //add Adafruit Motor Shield library
#include <Servo.h> //add Servo Motor library
#include <NewPing.h> //add Ultrasonic sensor library
#define TRIG_PIN A0 // Pin A0 on the Motor Drive Shield soldered to the ultrasonic sensor
#define ECHO_PIN A1 // Pin A1 on the Motor Drive Shield soldered to the ultrasonic sensor
#define MAX_DISTANCE 300 // sets maximum useable sensor measuring distance to 300cm
#define MAX_SPEED 160 // sets speed of DC traction motors to 150/250 or about 70% of full speed - to get power drain down.
#define MAX_SPEED_OFFSET 40 // this sets offset to allow for differences between the two DC traction motors
#define COLL_DIST 30 // sets distance at which robot stops and reverses to 30cm
#define TURN_DIST COLL_DIST+20 // sets distance at which robot veers away from object
NewPing sonar(TRIG_PIN, ECHO_PIN, MAX_DISTANCE); // sets up sensor library to use the correct pins to measure distance.
AF_DCMotor leftMotor1(1, MOTOR12_1KHZ); // create motor #1 using M1 output on Motor Drive Shield, set to 1kHz PWM frequency
AF_DCMotor leftMotor2(2, MOTOR12_1KHZ); // create motor #2, using M2 output, set to 1kHz PWM frequency
AF_DCMotor rightMotor1(3, MOTOR34_1KHZ);// create motor #3, using M3 output, set to 1kHz PWM frequency
AF_DCMotor rightMotor2(4, MOTOR34_1KHZ);// create motor #4, using M4 output, set to 1kHz PWM frequency
Servo myservo; // create servo object to control a servo
int leftDistance, rightDistance; //distances on either side
int curDist = 0;
String motorSet = "";
int speedSet = 0;
//-------------------------------------------- SETUP LOOP ----------------------------------------------------------------------------
void setup() {
myservo.attach(10); // attaches the servo on pin 10 (SERVO_1 on the Motor Drive Shield to the servo object
myservo.write(90); // tells the servo to position at 90-degrees ie. facing forward.
delay(1000); // delay for one seconds
}
//------------------------------------------------------------------------------------------------------------------------------------
//---------------------------------------------MAIN LOOP ------------------------------------------------------------------------------
void loop() {
myservo.write(90); // move eyes forward
delay(90);
curDist = readPing(); // read distance
if (curDist < COLL_DIST) {changePath();} // if forward is blocked change direction
moveForward(); // move forward
delay(500);
}
//-------------------------------------------------------------------------------------------------------------------------------------
void changePath() {
moveStop(); // stop forward movement
myservo.write(36); // check distance to the right
delay(500);
rightDistance = readPing(); //set right distance
delay(500);
myservo.write(144); // check distace to the left
delay(700);
leftDistance = readPing(); //set left distance
delay(500);
myservo.write(90); //return to center
delay(100);
compareDistance();
}
void compareDistance() // find the longest distance
{
if (leftDistance>rightDistance) //if left is less obstructed
{
turnLeft();
}
else if (rightDistance>leftDistance) //if right is less obstructed
{
turnRight();
}
else //if they are equally obstructed
{
turnAround();
}
}
//-------------------------------------------------------------------------------------------------------------------------------------
int readPing() { // read the ultrasonic sensor distance
delay(70);
unsigned int uS = sonar.ping();
int cm = uS/US_ROUNDTRIP_CM;
return cm;
}
//-------------------------------------------------------------------------------------------------------------------------------------
void moveStop() {leftMotor1.run(RELEASE); leftMotor2.run(RELEASE); rightMotor1.run(RELEASE); rightMotor2.run(RELEASE);} // stop the motors.
//-------------------------------------------------------------------------------------------------------------------------------------
void moveForward() {
motorSet = "FORWARD";
leftMotor1.run(FORWARD); // turn it on going forward
leftMotor2.run(FORWARD); // turn it on going forward
rightMotor1.run(FORWARD); // turn it on going forward
rightMotor2.run(FORWARD); // turn it on going forward
for (speedSet = 0; speedSet < MAX_SPEED; speedSet +=2) // slowly bring the speed up to avoid loading down the batteries too quickly
{
leftMotor1.setSpeed(speedSet);
leftMotor2.setSpeed(speedSet);
rightMotor1.setSpeed(speedSet);
rightMotor2.setSpeed(speedSet);
delay(5);
}
}
//-------------------------------------------------------------------------------------------------------------------------------------
void moveBackward() {
motorSet = "BACKWARD";
leftMotor1.run(BACKWARD); // turn it on going backward
leftMotor2.run(BACKWARD); // turn it on going backward
rightMotor1.run(BACKWARD); // turn it on going backward
rightMotor2.run(BACKWARD); // turn it on going backward
for (speedSet = 0; speedSet < MAX_SPEED; speedSet +=2) // slowly bring the speed up to avoid loading down the batteries too quickly
{
leftMotor1.setSpeed(speedSet);
leftMotor2.setSpeed(speedSet);
rightMotor1.setSpeed(speedSet);
rightMotor2.setSpeed(speedSet);
delay(5);
}
}
//-------------------------------------------------------------------------------------------------------------------------------------
void turnRight() {
motorSet = "RIGHT";
leftMotor1.run(FORWARD); // turn motor 1 forward
leftMotor2.run(FORWARD); // turn motor 2 forward
rightMotor1.run(BACKWARD); // turn motor 3 backward
rightMotor2.run(BACKWARD); // turn motor 4 backward
rightMotor1.setSpeed(speedSet+MAX_SPEED_OFFSET);
rightMotor2.setSpeed(speedSet+MAX_SPEED_OFFSET);
delay(1500); // run motors this way for 1500
motorSet = "FORWARD";
leftMotor1.run(FORWARD); // set both motors back to forward
leftMotor2.run(FORWARD);
rightMotor1.run(FORWARD);
rightMotor2.run(FORWARD);
}
//-------------------------------------------------------------------------------------------------------------------------------------
void turnLeft() {
motorSet = "LEFT";
leftMotor1.run(BACKWARD); // turn motor 1 backward
leftMotor2.run(BACKWARD); // turn motor 2 backward
leftMotor1.setSpeed(speedSet+MAX_SPEED_OFFSET);
leftMotor2.setSpeed(speedSet+MAX_SPEED_OFFSET);
rightMotor1.run(FORWARD); // turn motor 3 forward
rightMotor2.run(FORWARD); // turn motor 4 forward
delay(1500); // run motors this way for 1500
motorSet = "FORWARD";
leftMotor1.run(FORWARD); // turn it on going forward
leftMotor2.run(FORWARD); // turn it on going forward
rightMotor1.run(FORWARD); // turn it on going forward
rightMotor2.run(FORWARD); // turn it on going forward
}
//-------------------------------------------------------------------------------------------------------------------------------------
void turnAround() {
motorSet = "RIGHT";
leftMotor1.run(FORWARD); // turn motor 1 forward
leftMotor2.run(FORWARD); // turn motor 2 forward
rightMotor1.run(BACKWARD); // turn motor 3 backward
rightMotor2.run(BACKWARD); // turn motor 4 backward
rightMotor1.setSpeed(speedSet+MAX_SPEED_OFFSET);
rightMotor2.setSpeed(speedSet+MAX_SPEED_OFFSET);
delay(1700); // run motors this way for 1700
motorSet = "FORWARD";
leftMotor1.run(FORWARD); // set both motors back to forward
leftMotor2.run(FORWARD);
rightMotor1.run(FORWARD);
rightMotor2.run(FORWARD);
}
Only If someone can please help me! 
