Arduino 4WD Robot ?>

Arduino 4WD Robot

A while back I purchased the Sainsmart 4WD Arduino robot.  I had virtually zero experience building or programming an autonomous robot so I thought the project would be a great learning experience.

Sainsmart Arduino Robot

The Kit includes a 4WD robot chassis, Arduino Mega 2560, L298N dual H Bridge driver, sensor shield, wiring and various other items needed.

I decided to document the builds and improvements from start to finish via my YouTube videos so others could benefit.  I guess they were pretty good because Sainsmart linked almost all of them to the product listings on their web page :)

Arduino DIY robot

Here you will find the entire playlist of videos on the build and slowly improving the code:

Here is the newest video discussing the code below!

I found immediately after assembly that the example code supplied at the time really did not work…at all.  So I’ve been steadily improving my version of the code and here it is for all to use.  Take it, modify it and share it!

Please consider posting in the Forum if you found this code helpful.  Really enjoy hearing from all of you.

Update: I have a GIT repo with multiple iterations of this code HERE

Code below dates from May 2014 to include Bluetooth control (I have lost all track so I’m leaving this code here too) Get the newest one from GitHub above.

/* 
Following code by EricWillaim
All build information, code and forum posts/discussion can be found at:
http://mkme.org

Dedicated build page:
http://www.mkme.org/index.php/arduino-sainsmart-4wd-robot/

This is my attempt at programming the Sainsmart 4WD robot
So far it now checks for a new direction periodically and performs
backup and turn functions as in reaction to the environment it is presented.
It is by far not optimized code- but works for now :)
I will update this periodically as I get time to learn new methods and improve the code. 
Please check out my Youtube videos here and consider a thumbs up if this helped you!
Youtube : http://www.youtube.com/user/Shadow5549

Some portions of this code adapted from:
http://www.duino-robotics.com/

V9 Dec 12 2013:
Added a forward distance check after turns- will continue to turn if distance still too small
Minor Tweaks but still using delay functions

V10 May 2014
Added support for Roam mode- serial commands will toggle roam versus individual driving commands
*/

#include <Servo.h> //servo library
#include "pitches.h"// used for the speaker output
#define SPEAKER 4// Speaker Pin

Servo headservo;
const int EchoPin = 2; // Ultrasonic signal input
const int TrigPin = 3; // Ultrasonic signal output
const int leftmotorpin1 = 8; //signal output of Dc motor driven plate
const int leftmotorpin2 = 9;
const int rightmotorpin1 = 6;
const int rightmotorpin2 = 7;
const int HeadServopin = 5; // signal input of headservo
const int maxStart = 800; //run dec time- no clue what this is
unsigned long time; //used for upcoming improvements (time used instead of loops)
unsigned long time1; //used for upcoming improvements (time used instead of loops)
int add= 0; //used for nodanger loop count
int add1= 0;  //used for nodanger loop count
int roam = 1;
int currDist = 5000; // distance
boolean running = false;// This is from old code examples

void setup() {
  //initialize beeps
  tone(SPEAKER, NOTE_C7, 100);
  delay(500);
  tone(SPEAKER, NOTE_C6, 100);
  tone(SPEAKER, NOTE_C7, 100);
  delay(500);
  tone(SPEAKER, NOTE_C6, 100);
  tone(SPEAKER, NOTE_C7, 100);
  delay(500);
  tone(SPEAKER, NOTE_C6, 100);
  //End Initialize Beeps
  
Serial.begin(9600); // Enables Serial monitor for debugging purposes
Serial.println("Serial Data Initiated!"); // Test the Serial communication
pinMode(EchoPin, INPUT);//signal input port

//signal output port
for (int pinindex = 3; pinindex < 10; pinindex++) {
pinMode(pinindex, OUTPUT); // set pins 3 to 10 as outputs
}

// headservo interface
headservo.attach(HeadServopin);
//start buffer movable head
headservo.write(160);
delay(1000);
headservo.write(20);
delay(1000);
headservo.write(90);
delay(1000);
return;
}
void loop() 

  {
  if (Serial.available() > 0) 
  {
    int data = Serial.read();	//read serial input commands
    switch(data)
    {
    case 'w' : 
      Serial.println("Rolling!");
      moveForward(); 
      break;
    case 'x' : 
      backup(); 
      buzz(); 
      break;
    case 'a' : 
      body_lturn(); 
      buzz(); 
      break;
    case 'd' : 
      body_rturn(); 
      buzz(); 
      break;
    case 's' : 
      totalhalt(); 
      break;
    case 'r' : 
      toggleRoam(); 
      buzz(); 
      break;
    
      }
  }
  
  if(roam == 0){ //just listen to serial commands and wait
   // Do something else if you like
  }
  else if(roam == 1){  //If roam active- drive autonymously
  
  
  
//time = millis(); // Sets "time" to current system time count
currDist = MeasuringDistance(); //measure front distance
Serial.print("Current Forward Distance: ");
//Serial.println(currDist);
if(currDist > 35) {
  add = (add1++);// Start adding up the loop count done in nodanger
nodanger();
Serial.println("Nodanger: ");
}
else if(currDist < 35){
  //add=0;
  Serial.println("Forward Blocked- Decide Which Way");
  backup();
  whichway();
  
}
  }
  
  }
//measure distance, unit “cm”
long MeasuringDistance() {
long duration;
//pinMode(TrigPin, OUTPUT);
digitalWrite(TrigPin, LOW);
delayMicroseconds(2);
digitalWrite(TrigPin, HIGH);
delayMicroseconds(5);
digitalWrite(TrigPin, LOW);
//pinMode(EchoPin, INPUT);
duration = pulseIn(EchoPin, HIGH);
return duration / 29 / 2;
}
  

// forward
void moveForward() {
analogWrite(leftmotorpin1, 0);//Changed these to analog write for slower
analogWrite(leftmotorpin2, 120);
analogWrite(rightmotorpin1, 0);
analogWrite(rightmotorpin2, 120);
}

void toggleRoam(){
if(roam == 0){
   roam = 1;
   Serial.println("Activated Roam Mode");
  }
  else{
    roam = 0;
    totalhalt();
    Serial.println("De-activated Roam Mode");
  }
}

void nodanger() {
running = true;// Do I need these?
analogWrite(leftmotorpin1, 0);//Changed these to analog write for slower
analogWrite(leftmotorpin2, 120);
analogWrite(rightmotorpin1, 0);
analogWrite(rightmotorpin2, 120);
if (add1 > 38 ) whichway(); // Robot will stop and check direction every X loops through nodanger then resets in totalhalt (40 is good)
return;
}

//backward
void backup() {
add1=0; // resets the counter for the nodanger loops
running = true;//Do I need these?
digitalWrite(leftmotorpin1, HIGH);
digitalWrite(leftmotorpin2, LOW);
digitalWrite(rightmotorpin1, HIGH);
digitalWrite(rightmotorpin2, LOW);
Serial.println("Backing Up");
fart();
}

//choose which way to turn
void whichway() {
running = true;//Do I need these?
totalhalt();
headservo.write(160);
delay(900);
int lDist = MeasuringDistance(); // check left distance
Serial.println("checking left");
Serial.println(lDist);
headservo.write(20); // turn the servo right
delay(900);
int rDist = MeasuringDistance(); // check right distance
Serial.println("checking right");
Serial.println(rDist);
//totalhalt(); //  Do I need this???  Used to be used to centre the servo
if(lDist < rDist) {
Serial.println("Decided Right Is Best");
buzz();// Make him talk
body_rturn();
totalhalt();
currDist = MeasuringDistance(); //measure front distance
if(currDist < 45) body_rturn();  //if front distance still too small- turn again
}
else{
Serial.println("Decided Left Is Best");
  buzz();// Make him talk
  body_lturn();
  totalhalt();
  currDist = MeasuringDistance(); //measure front distance
  if(currDist < 45) body_lturn();// if front distance still too small- turn again
   }
return;
} 

void totalhalt() {
digitalWrite(leftmotorpin1, HIGH);
digitalWrite(leftmotorpin2, HIGH);
digitalWrite(rightmotorpin1, HIGH);
digitalWrite(rightmotorpin2, HIGH);
Serial.println("Totalhalt!");
headservo.write(90); // set servo to face forward
delay(250);
running = false;//Do I need these?
add1=0; // resets the counter for the nodanger loops
return;
}

//turn left
void body_lturn() {
running = true;
analogWrite(leftmotorpin1, 0);
analogWrite(leftmotorpin2, 220);
analogWrite(rightmotorpin1, 220);
analogWrite(rightmotorpin2, 0);
Serial.println("Turning Left");
delay(400);
}

//turn right
void body_rturn() {
running = true;
analogWrite(leftmotorpin1, 220);
analogWrite(leftmotorpin2, 0);
analogWrite(rightmotorpin1, 0);
analogWrite(rightmotorpin2, 220);
Serial.println("Turning Right");
delay(400);
}

void buzz(){
tone(SPEAKER, NOTE_C7, 100);
delay(50);
tone(SPEAKER, NOTE_C6, 100);
}

void fart(){
 tone(SPEAKER, NOTE_C2, 200);
 delay(50);
 tone(SPEAKER, NOTE_C1, 400); 
 delay(100);
 noTone(SPEAKER);
}

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