Scott Beasley
Published © CC BY-SA

Simple Object avoider robot the using Actobotics Runt

Using the Actobotics Runt Rover Peewee chassis kit and an Arduino controller, motor driver and sensors from eBay or other vendors.

BeginnerFull instructions provided11,771
Simple Object avoider robot the using Actobotics Runt

Things used in this project

Hardware components

Peewee Runt Rover
×1
Arduino UNO
Arduino UNO
×1
Arduino Arudiono Motor Shield R3
×1
SG90 Micro-servo motor
SG90 Micro-servo motor
×1
Ultrasonic Sensor - HC-SR04 (Generic)
Ultrasonic Sensor - HC-SR04 (Generic)
×1
Female to Female jumper wires
×1

Story

Read more

Code

Basic Arduino obstacle avoider

C/C++
/*
   Basic Arduino obstacle avoider.

   Goal in life...
      Moves forward looking for obstacles to avoid :-)

   Use to get started for a SHR (Start here robot) (http://letsmakerobots.com/)

   Written by Scott Beasley - 2015
   Free to use or modify. Enjoy.
*/

/*
   Uses the MotorShield library. It works with the Arduino Motor shield R3.

   Download from https://github.com/jscottb/MotorShield or clone the zip from
   https://github.com/jscottb/MotorShield/archive/master.zip
   Unzip and copy to your Arduino library folder or follow the instructions
   here: http://arduino.cc/en/guide/libraries

   Note: You may need to remove the '-master' from the archive file name to add
   the library
*/

// Using the Arduino Motor shield R3 (http://arduino.cc/en/Main/ArduinoMotorShieldR3)
#include <MotorShield.h>
#include <Servo.h>

// Defines for the distance reading function of the bot.
#define turn() (left_dist >= right_dist) ? go_left () : go_right ()
#define microsecondsToCentimeters(microseconds) (unsigned long)microseconds / 29.1 / 2.0
#define MIN_ACTION_DIST 5 // 5 cm
// Change these defines if you use differnt pins
#define ECHO_PIN 2  // Digital pin 2.
#define TRIGGER_PIN 5 // Digital pin 5

// Speed defines
#define MAXFORWARDSPEED 190 // Max speed we want moving forward
#define MAXBACKWARDSPEED 130 // Max reverse speed

// Various time delays used for driving and servo
#define TURNDELAY 450
#define BACKUPDELAY 300
#define SERVOMOVEDELAY 200
#define SERVOSEARCHDELAY 85

/*
   Globals area. Try to keep them to a minimum :-)
*/

// Create the motor and servo objects with use to interface with
MS_DCMotor motor_left (MOTOR_A); // Create Left motor object
MS_DCMotor motor_right (MOTOR_B); // Create Right motor object
Servo sensor_servo; // Create a servo object for our distance sensor

byte sweep_pos = 0; // Current position of the sensor servo
byte pos_index = 90;
unsigned long left_dist, right_dist; // Distance measured left and right

void setup ( )
{
   Serial.begin (9600); // Set Serial monitor at 9600 baud
   Serial.println ("My SHR bot is starting up!");

   // Make sure the motors are off at start
   halt ( );

   sensor_servo.attach (6); // Attach the servo to digital pin 6
   sensor_servo.write (90); // Set the servo to the middle (neutral) pos

   // Set modes for distance sensor pins
   pinMode (ECHO_PIN, INPUT);  // Set echo pin as input
   pinMode (TRIGGER_PIN, OUTPUT); // Set trigger pin as output

   // Delay to give user time to make adjustments.  Remove after done.
   delay (30000);
}

void loop ( )
{
   unsigned long dist_fwd;

   // Rotate the distance sensor as we drive along
   rotate_sensor ( );

   // Give the servo time to get to position and get setted
   delay (SERVOSEARCHDELAY);

   // Get a reading from the current sensor direction
   dist_fwd = ping ( );
   Serial.print ("Distance sensor reading: ");
   Serial.println (dist_fwd);

   // Go forward while nothing is in the distance sensors read area
   if (dist_fwd > MIN_ACTION_DIST || dist_fwd == 0)
   {
      go_forward ( );
   }
   else // There is something in the sensors read area
   {
      halt ( ); // Stop!
      go_backward ( ); // Back up a bit
      delay (BACKUPDELAY);
      halt ( ); // Stop!

      sensor_read ( ); // Read distance left and right

      turn ( ); // Turn toward the clearest path
      delay (TURNDELAY);
      halt ( );
   }
}

// Read the sensor after we find something in the way. This helps find a new
// path
void sensor_read ( )
{
   Serial.println ("Server at 40 deg...");
   sensor_servo.write (40);
   delay (SERVOMOVEDELAY);
   right_dist = ping ( ); //Look to the right

   Serial.println ("Servo at 140 deg...");
   sensor_servo.write (140);
   delay (SERVOMOVEDELAY);
   left_dist = ping ( ); // Look to the left

   // Set the servo back to the center pos
   Serial.println ("Servo at 90 deg...");
   sensor_servo.write (90);
}

// Rotate the sensor servo at 45deg increments
void rotate_sensor ( )
{
   if (sweep_pos <= 0) {
      pos_index = 45;
   }
   else if (sweep_pos >= 180) {
      pos_index = -45;
   }

   Serial.print ("pos_index = ");
   Serial.println (pos_index);
   sweep_pos += pos_index;
   Serial.print ("sweep_pos = ");
   Serial.println (sweep_pos);
   sensor_servo.write (sweep_pos);
}

// Read the HC-SR04 uSonic sensor
unsigned long ping ( )
{
   // Trigger the uSonic sensor (HC-SR04) to send out a ping
   digitalWrite (TRIGGER_PIN, LOW);
   delayMicroseconds (5);
   digitalWrite (TRIGGER_PIN, HIGH);
   delayMicroseconds (10);
   digitalWrite (TRIGGER_PIN, LOW);

   // Measure how long the ping took and convert to cm's
   return (microsecondsToCentimeters (pulseIn (ECHO_PIN, HIGH)));
}

void go_forward ( )
{
   Serial.println ("Going forward...");
   motor_left.setSpeed (MAXFORWARDSPEED);
   motor_right.setSpeed (MAXFORWARDSPEED);
   motor_left.run (FORWARD|RELEASE);
   motor_right.run (BACKWARD|RELEASE);
}

void go_backward ( )
{
   Serial.println ("Going backward...");
   motor_left.setSpeed (MAXBACKWARDSPEED);
   motor_right.setSpeed (MAXBACKWARDSPEED);
   motor_left.run (BACKWARD|RELEASE);
   motor_right.run (FORWARD|RELEASE);
}

void go_left ( )
{
   Serial.println ("Going left...");
   motor_left.setSpeed (MAXFORWARDSPEED);
   motor_right.setSpeed (MAXFORWARDSPEED);
   motor_left.run (BACKWARD|RELEASE);
   motor_right.run (BACKWARD|RELEASE);
}

void go_right ( )
{
   Serial.println ("Going right...");
   motor_left.setSpeed (MAXFORWARDSPEED);
   motor_right.setSpeed (MAXFORWARDSPEED);
   motor_left.run (FORWARD|RELEASE);
   motor_right.run (FORWARD|RELEASE);
}

void halt ( )
{
   Serial.println ("Halt!");
   motor_left.setSpeed (0);
   motor_right.setSpeed (0);
   motor_left.run (BRAKE);
   motor_right.run (BRAKE);
}

Github

https://github.com/jscottb/MotorShield

Credits

Scott Beasley

Scott Beasley

9 projects • 61 followers
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Comments

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  • Arduino
  • Robotics