RobotControl Find obstacles

Find obstacles

This example shows how to make find the obstacles at your Robot. 
By attaching a ultrasonic rangefinder, the robot can find the obstacles and turn around to avoid collision.

Hardware Required

  • Arduino Robot
  • SD-card
  • Ultrasonic rangefinder
  • Cable to plug the Ultrasonic sensor


The detailed instructions are shown down:

  • Connect the Ultrasonic ranger to TK1.
  • Fix the sensor to the front of the robot
  • Upload this sketch.
  • Unplug USB.
  • Turn on power.
  • Put the robot on the floor
  • The robot will move around, avoiding obstacles in front of it.

Find obstacles with the Arduino Robot


The sketch use the Wire.h, SPI.h and ArduinoRobot.h libraries. 
In this sketch the sensor is set to find an obstacle at 20cm of distance. 
You can change it, modifying the command line:" while (getDistance() < 20)", replacing 20 with an other value in centimeters.

The complete code and its detailed description are shown down.

/* Runaway Robot
* Arduino Robot
* US range finder like Maxbotix EZ10, with analog output
created 1 May 2013
by X. Yang
modified 12 May 2013
by D. Cuartielles
This example is in the public domain
// include the robot library
#include <ArduinoRobot.h>
#include <Wire.h>
#include <SPI.h>
int sensorPin = M1; // pin is used by the sensor
void setup() {
// initialize the Robot, SD card, and display
// draw a face on the LCD screen
void loop() {
// If the robot is blocked, turn until free
while (getDistance() < 20) { // If an obstacle is less than 20cm away
  setFace(false); //shows an unhappy face
  Robot.motorsStop(); // stop the motors
  delay(1000); // wait for a moment
  Robot.turn(90); // turn to the right and try again
  setFace(true); // happy face
// if there are no objects in the way, keep moving
Robot.motorsWrite(255, 255);
// return the distance in cm
float getDistance() {
// read the value from the sensor
int sensorValue = Robot.analogRead(sensorPin);
//Convert the sensor input to cm.
float distance_cm = sensorValue * 1.27;
return distance_cm;
// make a happy or sad face
void setFace(boolean onOff) {
if (onOff) {
  // if true show a happy face
  Robot.background(0, 0, 255);
  Robot.setCursor(44, 60);
  Robot.stroke(0, 255, 0);
} else {
  // if false show an upset face
  Robot.background(255, 0, 0);
  Robot.setCursor(44, 60);
  Robot.stroke(0, 255, 0);