Planet Arduino

This is a repost of a previous project. I am still working to get the older post back online from when we upgraded Wordpress.

The robot was basically built using a Parallax Boe Bot chassis. Rather than using the Basic Stamp we added an Arduino with a proto shield to control the robot functions.

You can use any type of chassis for this project. The robot moves about using a ping sonar and IR sensors to avoid running into any objects. As you can see in the video, it was a bit thrown off by our kitten. We added additional items such as a wireless camera that sends audio/video back to our TV.The original design for this was created by an Instructable’s member and can be found here.

Items you will need for this project:

• Arduino/Freeduino or Breadboard Arduino
• (3) 3-Wire Sensor Cables
• Breadboard (small) or Breadboard (large)
• Protoshield
• (3) Sharp IR Sensors
• 5V 1A Switching voltage regulator
• Various lengths of wire
• LED
• 220 Ohm resistor
• Optional – 4 AA Battery Holder
• Piezo Speaker/Element
• Parallax Ping))) Ultrasonic Rangefinder
• (2) Parallax Continuous Rotation Servos
• 1 Parallax Standard Rotation Servos
• 9.6V Ni-Cd Rechargeable Battery (or any other 8-AA cell battery pack/any rechargeable battery pack above 9V)
• Optional Method: Dual Motor Breakout and 2 DC Motors (Tutorial Available Here)

Arduino Autonomous Robot

The standard servo will be used to mount the Ping Rangefinder. This will give you a back and forth sweep motion as the robot travels around. The two continuous rotation servos are used for the wheels. You do not need to use the Parallax brand of servos, other brands will work. You may have to adjust the PWM values in the source code to go with the servos you are using.

It is also possible to use DC motors and edit the code, which would be considerably cheaper. You could use a SN754410 Quad Half H-Bridge to drive two DC motors. Tutorial for how to do this is available here.

The Arduino hook up is pretty simple. You will have the following:

• Pin (Analog) 0: Left Sensor
• Pin (Analog) 1: Center Sensor
• Pin (Analog) 2: Right Sensor
• Pin 5: Pan Servo
• Pin 6: Left Drive Servo
• Pin 7: Ultrasonic Rangefinder ( ‘Ping)))’ )
• Pin 9: Right Drive Servo
• Pin 11: Piezo Speaker

Shield Close-up

Radioshack sells an RC car battery as well as connector repair kit. You can solder the repair kit connector onto the shield, and then be able to hook up your battery to power the servos with. You can use a separate battery holder to power the Arduino.

Make all your connections onto the shield. This way everything can remain in place if you need to use your Arduino for something else and save you from needing to tear apart everything.

for power to the shield, you won’t need any extra filter capacitors since the 5V switching  regulator has them built in. We used a small project box to hold the battery in place, and was able to attach the wireless camera on top of it.

The Arduino and camera are power source 1, while the servos and sensors are power source 2 (the RC battery). A small piece of PVC pipe mounted onto a cable clip will help you to keep your wires all organized to a central point and be less likely to get caught or tangled up into something as the robot is moving around.

Arduino Sketch

// Begin Robot Code
int micVal;
int cdsVal;
int irLval;  // Left IR
int irCval;  // Center IR
int irRval;  // Right IR

int i;   // Generic Counter
int x;  // Generic Counter
int PLval;  // Pulse Width for Left Servo
int PRval;  // Pulse Width for Right Servo
int cntr;  // Generic Counter Used for Determining amt. of Object Detections
int counter; // Generic Counter
int clrpth;  // amt. of Milliseconds Of Unobstructed Path
int objdet;  // Time an Object was Detected
int task;  // Routine to Follow for Clearest Path
int pwm;  // Pulse Width for Pan Servo
boolean add;  // Whether to Increment or Decrement PW Value for Pan Servo
int distance;  // Distance to Object Detected via Ultrasonic Ranger
int oldDistance;  // Previous Distance Value Read from Ultrasonic Ranger

float scale = 1.9866666666666666666666666666667;  // *Not Currently Used*

int LeftPin = 6;  // Left Servo
int RightPin = 9;  // Right Servo
int PiezoPin = 11;  // Piezo
int PingServoPin = 5;  // Pan Servo
int irLPin = 0;            // Analog 0; Left IR
int irCPin = 1;            // Analog 1; Center IR
int irRPin = 2;            // Analog 2; Right IR

int ultraSoundSignal = 7; // Ultrasound signal pin
int val = 0;              // Used for Ultrasonic Ranger
int ultrasoundValue = 0;  // Raw Distance Val
int oldUltrasoundValue;  // *Not used*
int pulseCount;        // Generic Counter
int timecount = 0; // Echo counter
int ledPin = 13; // LED connected to digital pin 13

#define BAUD 9600
#define CmConstant 1/29.034

void setup() {
  Serial.begin(9600);
  pinMode(PiezoPin, OUTPUT);
  pinMode(ledPin, OUTPUT);
  pinMode(LeftPin, OUTPUT);
  pinMode(RightPin, OUTPUT);
  pinMode(PingServoPin, OUTPUT);
  pinMode(irLPin, INPUT);
  pinMode(irCPin, INPUT);
  pinMode(irRPin, INPUT);
  for(i = 0; i < 500; i++) {
    digitalWrite(PiezoPin, HIGH);
    delayMicroseconds(1000);
    digitalWrite(PiezoPin, LOW);
    delayMicroseconds(1000);
  }
  for(i = 0; i < 20; i++) {
  digitalWrite(PingServoPin, HIGH);
  delayMicroseconds(655 * 2);
  digitalWrite(PingServoPin, LOW);
  delay(20);
  }
  ultrasoundValue = 600;
  i = 0;
}

void loop()
{
  //Scan();
  Look();
  Go();
}
void Look() {
  irLval = analogRead(irLPin);
  irCval = analogRead(irCPin);
  irRval = analogRead(irRPin);
  //if(counter > 10) {
    //counter = 0;
    //readPing();
  //}
  if(irLval > 200) {
    PLval = 850;
    PRval = 820;
    x = 5;
    cntr = cntr + 1;
    clrpth = 0;
    objdet = millis();
  }
  else if(irCval > 200) {
    PLval = 850;
    PRval = 820;
    x = 10;
    cntr = cntr + 1;
    clrpth = 0;
    objdet = millis();
  }
  else if(irRval > 200) {
    PLval = 650;
    PRval = 620;
    x = 5;
    cntr = cntr + 1;
    clrpth = 0;
    objdet = millis();
  }
  else {
    x = 1;
    PLval = 850;
    PRval = 620;
    counter = counter + 1;
    clrpth = (millis() - objdet);
    if(add == true) {
      pwm = pwm + 50;
    }
    else if(add == false) {
      pwm = pwm - 50;
    }
    if(pwm < 400) {
      pwm = 400;
      add = true;
    }
    if(pwm > 950) {
      pwm = 950;
      add = false;
    }
    digitalWrite(PingServoPin, HIGH);
    delayMicroseconds(pwm * 2);
    digitalWrite(PingServoPin, LOW);
    delay(20);
    readPing();
    if(ultrasoundValue < 500) {
      cntr = cntr + 1;
      switch(pwm) {
        case 400:
          x = 7;
          PLval = 650;
          PRval = 650;
          Go();
          break;
        case 500:
          x = 10;
          PLval = 650;
          PRval = 650;
          Go();
          break;
        case 600:
          x = 14;
          PLval = 850;
          PRval = 850;
          Go();
          break;
        case 700:
          x = 10;
          PLval = 850;
          PRval = 850;
          Go();
          break;
        case 950:
          x = 7;
          PLval = 850;
          PRval = 850;
          Go();
          break;
      }
    }
  }
  //Serial.print("clrpth: ");
  //Serial.println(clrpth);
  //Serial.print("objdet: ");
  //Serial.println(objdet);
  //Serial.print("cntr: ");
  //Serial.println(cntr);
  if(cntr > 25 && clrpth < 2000) {
    clrpth = 0;
    cntr = 0;
    Scan();
  }
}
void Go() {
  for(i = 0; i < x; i++) {
    digitalWrite(LeftPin, HIGH);
    delayMicroseconds(PLval * 2);
    digitalWrite(LeftPin, LOW);
    digitalWrite(RightPin, HIGH);
    delayMicroseconds(PRval * 2);
    digitalWrite(RightPin, LOW);
    delay(20);
  }
}
void readPing() {  // Get Distance from Ultrasonic Ranger
 timecount = 0;
 val = 0;
 pinMode(ultraSoundSignal, OUTPUT); // Switch signalpin to output

/* Send low-high-low pulse to activate the trigger pulse of the sensor
 * -------------------------------------------------------------------
 */

digitalWrite(ultraSoundSignal, LOW); // Send low pulse
delayMicroseconds(2); // Wait for 2 microseconds
digitalWrite(ultraSoundSignal, HIGH); // Send high pulse
delayMicroseconds(5); // Wait for 5 microseconds
digitalWrite(ultraSoundSignal, LOW); // Holdoff

/* Listening for echo pulse
 * -------------------------------------------------------------------
 */

pinMode(ultraSoundSignal, INPUT); // Switch signalpin to input
val = digitalRead(ultraSoundSignal); // Append signal value to val
while(val == LOW) { // Loop until pin reads a high value
  val = digitalRead(ultraSoundSignal);
}

while(val == HIGH) { // Loop until pin reads a high value
  val = digitalRead(ultraSoundSignal);
  timecount = timecount +1;            // Count echo pulse time
}

/* Writing out values to the serial port
 * -------------------------------------------------------------------
 */

ultrasoundValue = timecount; // Append echo pulse time to ultrasoundValue

//serialWrite('A'); // Example identifier for the sensor
//printInteger(ultrasoundValue);
//serialWrite(10);
//serialWrite(13);

/* Lite up LED if any value is passed by the echo pulse
 * -------------------------------------------------------------------
 */

if(timecount > 0){
  digitalWrite(ledPin, HIGH);
}
} 
void Scan() {   // Scan for the Clearest Path
  oldDistance = 30;
  task = 0;
  for(i = 1; i < 5; i++) {
    switch(i) {
      case 1:
        //Serial.println("Pos. 1");
        pwm = 1125;    ///  incr. by 100 from 1085
        break;
      case 2:
        //Serial.println("Pos. 2");
        pwm = 850; //// increased by 100 from 850
        break;
      case 3:
        //Serial.println("Pos. 3");
        pwm = 400;
        break;
      case 4:
        //Serial.println("Pos. 4");
        pwm = 235;
        break;
    }
    for(pulseCount = 0; pulseCount < 20; pulseCount++) {  // Adjust Pan Servo and Read USR
      digitalWrite(PingServoPin, HIGH);
      delayMicroseconds(pwm * 2);
      digitalWrite(PingServoPin, LOW);
      readPing();
      delay(20);
    }
    distance = ((float)ultrasoundValue * CmConstant);   // Calculate Distance in Cm
    if(distance > oldDistance) {  // If the Newest distance is longer, replace previous reading with it
      oldDistance = distance;
      task = i;   // Set task equal to Pan Servo Position
    }
  }
  //Serial.print("Task: ");
  //Serial.println(task);
  //Serial.print("distance: ");
  //Serial.println(distance);
  //Serial.print("oldDistance: ");
  //Serial.println(oldDistance);
  distance = 50;  // Prevents Scan from Looping
  switch(task) {   // Determine which task should be carried out
    case 0:  // Center was clearest
      x = 28;
      PLval = (850);
      PRval = (850);
      Go();
      break;
    case 1:  // 90 degrees Left was Clearest
      x = 14;
      PLval = (650);
      PRval = (650);
      Go();
      break;
    case 2:  // 45 degrees left
      x = 7;
      PLval = (650);
      PRval = (650);
      Go();
      break;
    case 3:  // 45 degrees right
      x = 7;
      PLval = (850);
      PRval = (850);
      Go();
      break;
    case 4:  // 90 degrees right
      x = 14;
      PLval = (850);
      PRval = (850);
      Go();
      break;
  }
}

// End Robot Code