Sumo Bot with Ultrasonic Sensor

If you haven’t built or programmed your Sumo Bot, please go through those lessons first (04A-E on Workbench).

Not sure what an ultrasonic sensor is or how to program it? Go through the Ultrasonic Sensor lesson!

In this lesson, you’ll learn how to use the ultrasonic sensor with your sumo bot.

Once programmed, this sumo bot will have the full functionality of a normal sumo bot, but will have the added feature of being able to detect another sumo bot in front of it. Once it locks onto another robot, it rams toward it at full speed while making sure to avoid crossing the sumo ring.

You will need four female to female jumper cables, the ultrasonic sensor, and the Smart Inventor Board.

• The red wire is connected to the VCC pin on the ultrasonic sensor, which is connected to V on the Smart Inventor Board.
• The yellow wire is connected to the TRIG pin, which is connected to the Smart Inventor Board on pin 4 of PORTD.
• The white wire is connected to the ECHO pin, which is connected to the Smart Inventor Board on pin 5 of PORTD.
• The green wire is connected to the GND pin, which can be connected to any of the pins labeled G.

Please look at the diagram when you are finished wiring to make sure everything is connected properly!

First, begin the code by including the Smart Inventor library. Enter the following before void setup():

#include <SmartInventor.h>

Now declare the following variables. One will be for speed and the others will be used to measure the amount of time the robot goes backwards or forwards when it reaches the black line on the sumo ring.

int speedPercent = 50;
int backTime = 0;
int turnTime = 0;

Finally, assign the pin numbers the ultrasonic sensor will be connected to.

#define trigPin 29#define echoPin 30

Inside void setup(), assign the pin mode for both the trigger and echo pins.

pinMode(trigPin, OUTPUT);pinMode(echoPin, INPUT);

Declare all IR sensors on the Smart Inventor Board as inputs.

pinMode(11,INPUT);pinMode(12,INPUT);pinMode(13,INPUT);pinMode(14,INPUT);pinMode(15,INPUT);pinMode(16,INPUT);pinMode(17,INPUT);pinMode(18,INPUT);

Include the motors, and then have the sumo bot move forward.

SmartInventor.DCMotorUse();
SmartInventor.DCMove(forward, speedPercent);

Next, inside void loop(), create and set the variable currentDistance with the method getPingDistance(). This function will be made later on in the program, so don’t worry that you haven’t seen it yet.

int currentDistance = getPingDistance();

One way to know how far away the other robot is is to use the buzzer to change its sound frequency so the tone changes. The way we will do this is with this code.

if(currentDistance<50){
 SmartInventor.Buzz(2000-currentDistance*25, 18);
}

Next, type this in your program:

backTime++;
turnTime++;

if (backTime >= 200)
 backTime = 100;
if (turnTime >= 500)
 turnTime = 100;

Now we must tell the IR sensors what to do when they detect the black sumo ring line. Our program uses all of the IR sensors from pins 11 through pins 18, with the exception of pins 14 and 15. This is just in case one of the IR sensors fails to detect the line.

Type the following code into your program:

if (digitalRead(11) == LOW||
    digitalRead(12) == LOW||    digitalRead(13) == LOW)

IR sensors 11, 12, and 13 are all on the bottom lefthand side of the Smart Inventor Board. This if statement checks if these sensors do NOT detect any IR light. The pin stays LOW when no IR light is reflected, meaning the black ring has absorbed the infrared light from the sensor.

Now tell your sumo bot what to do when the sensor detects the black ring:

{
     //move backwards and buzz
     SmartInventor.DCMove(backward, speedPercent);
     SmartInventor.Buzz(1160, 12);
     delay(100 + backTime);

     //move to the right
     SmartInventor.DCMove(right, speedPercent);
     delay(100 + turnTime);
     
     //then move forward again
     SmartInventor.DCMove(forward, speedPercent);
 }

The robot will move back and buzz, turn to the right, and then move forward again. In this section, backTime and turnTimeextend the amount of time that delays last.

Now code the right IR sensors.

else if (digitalRead(17) == LOW||
    digitalRead(16) == LOW||
    digitalRead(18) == LOW)

  {
    //move backwards for some time
    SmartInventor.DCMove(backward, speedPercent);
    SmartInventor.Buzz(1160, 12);
    delay(100 + backTime);
    
    //move to the left
    SmartInventor.DCMove(left, speedPercent);
    delay(100 + turnTime);

    //then go forward
    SmartInventor.DCMove(forward, speedPercent);
    SmartInventor.Buzz(1900, 12);
  }

This section is similar to the other if statement, but now it just checks the sensors on the right side for the black ring.

Now program the ultrasonic sensor to ram forward at full speed if the object, but no black ring, is detected.

if(
   digitalRead(11) == HIGH &&
   digitalRead(12) == HIGH &&
   digitalRead(13) == HIGH &&
   digitalRead(16) == HIGH &&
   digitalRead(17) == HIGH &&
   digitalRead(18) == HIGH &&
   currentDistance<6)
   {
   SmartInventor.DCMove(forward, 100);
   }

This checks every sensor for no black ring, so all pins would be HIGH. This also checks if currentDistance is below 6 centimeters.

Now you will create the function that produces and returns the value of distance.  Outside of the curly braces of the loop, begin by typing

int getPingDistance()

You are now creating a method, or function, that when used in the program, the function returns an integer. Usually the word void is used, which just means that when the function is used, nothing is returned. This time, you will code the function that does the math and detecting of the distance.

{
long duration, distance; //create these two numbers

  digitalWrite(trigPin, LOW);
  //get the trigger pin set to low
  delayMicroseconds(2);

  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);   
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);

  return distance = (duration/2) / 29.1;
  //so the speedPercent of sound at sea level is 340.29 m / s
}

The sensor turns the trigger speaker on and off, emitting a pulse of high-frequency sound. The echo speaker waits and times the amount of time it takes. Once the time is known, the program does the math to find the distance traveled. This distance is then returned with the line

return distance = (duration/2) / 29.1;

You are now done coding!

This is what your final program should look like:

#include <SmartInventor.h>

int speedPercent = 50;
int  backTime = 0;
int  turnTime = 0;

#define trigPin 29
#define echoPin 30

void setup()
{

  //for the trig pin and echo pin
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  //<-LEFT □ □ □ □ □ □ □ □ RIGHT->
  //   11,12,13,14,15,16,17,18
  //BOTTOM SENSOR USE
  pinMode(11, INPUT);
  pinMode(12,INPUT);
  pinMode(13,INPUT);
  pinMode(14,INPUT);
  pinMode(15,INPUT);
  pinMode(16,INPUT);
  pinMode(17,INPUT);
  pinMode(18, INPUT);

  //This initiates the use of the motor
  SmartInventor.DCMotorUse();

  //Start of the motors to move forwards
  SmartInventor.DCMove(forward, speedPercent);
}

void loop()
{
 //grab the distance and save it as an integer
 int currentDistance = getPingDistance();

    //if the distance is less than 50cm 
    if(currentDistance<50)
    {   
    //make the buzzer buzz
    SmartInventor.Buzz(2000-currentDistance*25, 18);
    }

  backTime++;
  turnTime++;

  if (backTime >= 200) backTime = 100;
  if (turnTime >= 500) turnTime = 100;

  //If the IR sensors on the left side detect anything
  if (digitalRead(11) == LOW||
      digitalRead(12) == LOW||
      digitalRead(13) == LOW)
  {
    //move backwards and buzz
    SmartInventor.DCMove(backward, speedPercent);
    SmartInventor.Buzz(1160, 12);
    delay(100 + backTime);

    //move to the right
    SmartInventor.DCMove(right, speedPercent);
    delay(100 + turnTime);

    //then move forward again
    SmartInventor.DCMove(forward, speedPercent);
  }

  else if (digitalRead(17) == LOW||
           digitalRead(16) == LOW||
           digitalRead(18) == LOW)
  {
    //move backwards for some time
    SmartInventor.DCMove(backward, speedPercent);
    SmartInventor.Buzz(1160, 12);
    delay(100 + BackTime);

    //move to the left
    SmartInventor.DCMove(left, speedPercent);
    delay(100 + TurnTime);

    //then go forward
    SmartInventor.DCMove(forward, speedPercent);
    SmartInventor.Buzz(1900, 12);
  }

//If all IR sensors do not detect anyline on the floor
//and the distance of whatever object is less than 6cm
//drive forward
  if(
  digitalRead(11) == HIGH &&
  digitalRead(12) == HIGH &&
  digitalRead(13) == HIGH &&
  digitalRead(16) == HIGH &&
  digitalRead(17) == HIGH &&
  digitalRead(18) == HIGH &&
  currentDistance<6
     )
  {
    SmartInventor.DCMove(forward, 100);
    //drive at full speedPercent
  }

}

int getPingDistance()
{
  long duration, distance;//create these two numbers

  digitalWrite(trigPin, LOW);  
  //get the trigger pin set to low
  delayMicroseconds(2); // 

  digitalWrite(trigPin, HIGH);  
  delayMicroseconds(10); // 
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);

  return distance = (duration/2) / 29.1;
  //so the speedPercent of sound at sea level is 340.29 m / s

}