Sunday, 9 June 2013

How to Make an Obstacle Avoiding Robot

        In this post I am going to write the step-by-step procedure to build an obstacle avoiding Robot. I want to keep the cost of this Robot as low as possible so, I am going to use cheap and easily available Sensors like IR LED and Photodiode pair to detect the obstacles instead of expensive sensors like Sharp IR range finder or Ultrasonic transducer. Even though I am using the inexpensive sensors instead of expensive one the performance of the robot is good, you can find how it works from the below You tube vedio –




Materials required: 

      1)      Arduino
      2)      L293D Motor driver IC
      3)      DC Motors (two)
      4)      Wheels (two)
      5)      Castor ball
      6)      IR LED’s (at least 4)
      7)      Photodiodes (at least 2)
       8)     Chassis
       9)   PCB board
     11)   Connecting wires
     12)   9 Volt Batteries (two)
     13)   Double sided tape. 



Step-by-step Procedure To Make an Obstacle Avoiding Robot:

preparing the Sensors:

                      I had said before that, I am going to use IR LED’s and Photodiode as the Sensor to detect the obstacles. If you don’t know How we to use IR LED’s and Photodiode pair to detect the obstacles then, go through my previous post - How to use IR LED andPhotodiode pair with Arduino to detect obstacles.
                     For this project I am going to use the same circuit which I had used in my previous post but, I am going to add one extra IR LED to improve the sensor performance. So, we need two IR LED’s and a Photodiode to prepare one sensor.
                         I had arranged the two IR LED’s and a Photodiode in the PCB board such that the Photodiode is in the middle of two IR LED’s and I had soldered the component (IR LED’s, Photodiode and resistors) which looks like this.

How-to-make-an-obstacle-avoiding-robot

Each sensor has 5 wires two of them are connected to two IR LED’s, one to the Photodiode, one common ground and one wire is to take the readings from the sensor. The circuit diagram of the sensor is shown below. 

How-to-make-an-obstacle-avoiding-robot

L239D Motor driver IC:

            The L239D IC is a motor driver which is used to control two DC motors at a wide range of supply voltages (4.5 volts to 36 volts). Don’t connect the motors directly to Microcontroller the sharp spikes from the motor may damage the Arduino. The L239D IC has 16 legs. The connections of L239D with Arduino and DC Motors are shown in the following picture.



How-to-make-an-obstacle-avoiding-robot

Programming the Arduino:

            The Arduino source code for the Obstacle avoiding robot is presented below -

 int enable=2;         //Enable pins of L239D are connected to Arduino digital pin2  
 int motA1=4;          //pin-2 of L239D is connected to Arduino digital pin4  
 int motA2=5;          //pin-7 of L239D is connected to Arduino digital pin5   
 int motB1=6;          //pin-10 of L239D is connected to Arduino digital pin6  
 int motB2=7;          //pin-15 of L239D is connected to Arduino digital pin7  
 int senA1=8;          //sensorA first IR LED wire is connected to Arduino digital pin8  
 int senA2=9;          //sensorA second IR LED wire is connected to Arduino digital pin9  
 int senA3=10;         //sensorA Photodiode wire is connected to Arduino digital pin10  
 int senB1=11;         //sensorB first IR LED wire is connected to Arduino digital pin11  
 int senB2=12;         //sensorB second IR LED wire is connected to Arduino digital pin12  
 int senB3=13;         //sensorB Photodiode wire is connected to Arduino digital pin13  
 int senAread=0;       //wire connected between photodiode and 3 K resistor of sensorA is connected to Arduino analog pinA0  
 int senBread=1;       //wire connected between photodiode and 3 K resistor of sensorB is connected to Arduino analog pinA1  
 void setup()  
 {  
  pinMode(enable,OUTPUT);  
  digitalWrite(enable,HIGH);  
  pinMode(motA1,OUTPUT);  
  pinMode(motA2,OUTPUT);  
  pinMode(motB1,OUTPUT);  
  pinMode(motB2,OUTPUT);  
  pinMode(senA1,OUTPUT);  
  digitalWrite(senA1,HIGH);  
  pinMode(senA2,OUTPUT);  
  digitalWrite(senA2,HIGH);  
  pinMode(senA3,OUTPUT);  
  digitalWrite(senA3,HIGH);  
  pinMode(senB1,OUTPUT);  
  digitalWrite(senB1,HIGH);  
  pinMode(senB2,OUTPUT);  
  digitalWrite(senB2,HIGH);  
  pinMode(senB3,OUTPUT);  
  digitalWrite(senB3,HIGH);           
  digitalWrite(motA1,HIGH);         //  
  digitalWrite(motA2,LOW);          //In default mode both the motors will rotate forward   
  digitalWrite(motB1,HIGH);         //  
  digitalWrite(motB2,LOW);          //  
 }  
 void loop()  
 {  
  int val1=analogRead(senAread);       // val1 variable stores the readings from sensorA  
  int val2=analogRead(senBread);       // val2 variable stores the readings from sensorB  
  int diff=val1-val2;                  //calculating the difference of val1 and val2  
  if(val1<800 || val2<800)             //if any obstacle is detected by any one of the sensor  
  {  
    if(diff>=0)                        //if obstacle is present at right side of the robot  
    {  
     digitalWrite(motA2,HIGH);       //  
     digitalWrite(motA1,LOW);        //make the bot move backwards  
     digitalWrite(motB2,HIGH);       //  
     digitalWrite(motB1,LOW);        //  
     delay(1000);                    //wait for 1 second  
     digitalWrite(motB2,LOW);        //  
     digitalWrite(motB1,HIGH);       //turn left  
     delay(700);                     //wait for 700 milli seconds   
     digitalWrite(motA1,HIGH);       //  
     digitalWrite(motA2,LOW);        //move forward  
    }   
    else if(diff<0)                 //if obstacle is present at left side of the robot  
    {  
     digitalWrite(motA2,HIGH);       //  
     digitalWrite(motA1,LOW);        //make the bot move backwards  
     digitalWrite(motB2,HIGH);       //  
     digitalWrite(motB1,LOW);        //  
     delay(1000);                    //wait for one second  
     digitalWrite(motA2,LOW);        //  
     digitalWrite(motA1,HIGH);       //turn right  
     delay(700);                     //wait for 700 milli seconds  
     digitalWrite(motB1,HIGH);       //  
     digitalWrite(motB2,LOW);        //move forward  
    }    
  }  
  else                             //if no obstacle is present  
  {  
    digitalWrite(motA1,HIGH);       //  
    digitalWrite(motA2,LOW);        //  
    digitalWrite(motB1,HIGH);       // move forward  
    digitalWrite(motB2,LOW);        //  
  }  
 }  



How program works:

                       The program starts with the initialization of variables. In the “void setup()” method the pin mode is set to output and the pins of sensors are made HIGH i.e., the sensors are at ON condition. Then the motors are made to move forward as a default state. In the “void loop()” method the values from the sensors are stored in variables ‘val1’ and ‘val2’ after that their difference is calculated and stored in the variable ‘diff’ which tells us whether the obstacle is present at the right side or left side (if diff is > 0 the obstacle is present at right side and if diff is < 0 the obstacle is present at the left side of the bot). An if-else ladder is used to make the robot turn according to the obstacle position. If an obstacle is present at the left side of the robot then the bot moves backwards a bit after that turn right side and the moves forwards. If the obstacle is present at right side of the bot then the bot moves backwards a bit after that turns left and then moves forward.


Assembling:

                    Choose any available material for the chassis. I had used an aluminum frame from an old DVD-ROM  for the chassis of the robot. Connect the sensors one at the right-front corner and the other at the left-front corner of the chassis (you can add another sensor at the middle of these two to increase the performance of the robot) by using a double sided tape.


             Attach the castor ball in the middle at the front side of the robot with a double sided tape or any adhesive. Attach the two DC motors in the back left and right positions by using double sided tape or any adhesive. Then the bot will looks like in the below picture.

How-to-make-an-obstacle-avoiding-robot

                   Connect the sensors according to the circuit diagram shown above after that, connect the wires of L239D motor driver according to the pin diagram of L239D IC which is shown above (be careful with the directions of motor otherwise the bot will misbehave). After that Upload the Arduino code into the Arduino Microcontroller. That’s it your bot is ready for the first use.

                                     Is this post useful? Please feel free to comment.

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69 comments:

  1. yes this post is really useful

    ReplyDelete
  2. cani use readymade IR sensor module

    ReplyDelete
    Replies
    1. Yes, you can use ready made IR sensor module. I just want to minimize the budget so that I made the sensors myself

      Delete
  3. This comment has been removed by the author.

    ReplyDelete
    Replies
    1. IR sensor modules available in the market has 3 pins 1-Vin 2-Ground 3-analog output. Connect the Vin to digital output, connect ground pin to ground of Arduino and connect the analog output pin to analog pin of Arduino

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  4. This comment has been removed by the author.

    ReplyDelete
    Replies
    1. Connect the Vin pins of both the sensors to digital output pins 8 & 9 of Arduino and remove the following lines from the code 8,9,10,11,26,27,28,29,30,31,32&33.

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    2. thanks kranthi for ur patience thank u very much hope my project will success

      Delete
  5. This comment has been removed by the author.

    ReplyDelete
    Replies
    1. Inter change the wires of the motor which is not rotating in correct direction

      If you are still facing the problem then explain your problem more clearly or post a link to the vedio of your bot.

      Delete
  6. really this code is work
    because i want to drive my robot in bounded environment

    ReplyDelete
  7. very nice..but wer is d complete ckt diagram..???

    ReplyDelete
    Replies
    1. The final circuit digram is nothing but connecting these two ckt's to Arduino according to the pin numbers mentioned in the two pictures. Try to connect these two circuit with the Arduino according to the pin numbers mentioned. If you still have any problem then drop a comment I will post the full circuit diagram.

      Delete
  8. please post the complete ckt diagram...Thanks.

    ReplyDelete
    Replies
    1. I am busy with my MID exams. I will post the complete ckt with in 2 or 3 days

      Delete
  9. what would be the cost of arduino

    ReplyDelete
    Replies
    1. Check the latest prices of Original Arduino boards from - http://arduino.cc/en/Main/Products

      Check the prices of clone Arduino bords in India from - http://startrobotics.blogspot.in/2013/05/normal-0-false-false-false-en-us-x-none.html

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  10. is there any error in the code? because when I used it in my robot, the direction of the motors is not right.

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    Replies
    1. I already fix this but when I change 800 to other value, the error with regards to direction returns.

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    2. The value 800 doesn't have any direct or indirect relation to the direction of motors. The value 800 is only determines the detection range of obstacle. If you change the value from 800 to 700 or 600 or some other value less than 800 then the sensor detects the obstacle when the obstacle is much closer to the bot.

      Delete
  11. I would be happy, if you right something like remotely controlled robots even at a very basic level.

    ReplyDelete
  12. i used sharp ir sensor and follow your instructions but the direction of the wheels are not correct/

    ReplyDelete
    Replies
    1. inter-change the two motors i.e., left motor to right side and right motor to left

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  13. i interchanged and the motors stopped

    ReplyDelete
    Replies
    1. the motors are running but one side keeps getting forward then reverse repeatedly

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    2. motor turns to and fro means their might be some loose connections to the sensor. check for loose connections between sensor and arduino

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  14. can you please provide alternate code for utilization in a different microcontroller such as PIC ones...i am a beginner with microcontrollers so not very clear on code initialization and how much the syntax differs in different microcontrollers.

    ReplyDelete
  15. sirt,i wanted to use ultrasonic distance measuring sensor,instead of this,can you please tell me that what changes i should made in your programme for this.link of this sensor is given below
    http://dx.com/p/hc-sr04-ultrasonic-sensor-distance-measuring-module-133696

    ReplyDelete
    Replies
    1. If you want to build an obstacle avoiding bot using only one Ultrasonic sensor then its better to mount the sensor on Servo motor and scan for obstacles in 120 degrees. If you want me to post about that feel free to comment.

      Delete
  16. Sir, my group very interested with your project. Can you send me the circuit diagram ? tengkuamir15@gmail.com

    ReplyDelete
  17. hye..this post is really helpful..
    i'm thinking to apply your project with arduino line follower..
    can you help me??
    thank you very much..

    ReplyDelete
  18. This comment has been removed by the author.

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  19. give me code for this project using 8051 as i m begineer in microcontroller

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  20. we r trying to make obstacle avoider with rotating ir sensor...tell me something about it

    ReplyDelete
    Replies
    1. If you are trying to make a serious project (I mean not for hobby purpose) then its better to use Ultrasonic sensor or sharp IR sensor instead of normal IR led and photodiodes. because these sensors (Ultrasonic or Sharp IR sensors) performs better than normal IR led with photodiode.
      For the rotating purpose mount the sensor on a Servo motor.
      If you need any further help (in terms of code or circuit diagram or anything related to your project) don't hesitate to ask me.

      Delete
  21. sir, can i ask permission from you if i can use this as my school project. and if you're willing. can you help me if i have some queries, thank you sir.

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    Replies
    1. Sure you can use this as your school project.

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  22. did you used 2 sensors(using IR and photodiodes)

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  23. i wanted to talk to you regarding this matter but i dont know how. do you have something that you know that we can talk easier?

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    Replies
    1. you can contact me via my facebook account https://www.facebook.com/kranthi.ind

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    2. sir, done adding you on facebook. just wanted to know how did you connect the arduino with the dc motors and sensors, thank you in advance

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  24. i sent you message on facebook already, hope you'll reply, really need your help :)

    ReplyDelete
  25. thank all of you ,but help me, what i have to do if i will use two continuous servo motor rather than DC motor what i have to add or replace on the code and the circuit

    ReplyDelete
    Replies
    1. If you want to use Servo motors instead of DC motors then no need to use the L239D IC. You need to use the servo library to control the servo motors. just connect the red wire of your servo's to any Digital o/p pin and black wire to the Ground and the yellow/orange wire to PWM pin of your arduino and code the arduino accordingly

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  26. can you take a picture of the connection of the circuits, please. thanks

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    Replies
    1. I have sent the pics to your fb profile

      Delete
  27. did you use breadboard? im wondering how did you connect the circuits. can you draw all the connections if its okay

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    Replies
    1. Its not necessary to use bread board. You can solder the connections on pcb board

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  28. here's what i can say. our project wasnt able to work because maybe there's something wrong with the components because there is no available here. like the photodiode. but still, i want to thank the blogger, for helping me still to do our project. thumbs up for you sir. he's very approachable and very kind. ours didnt work but intend to help us, he even gave as alternative project.(coz we're chatting on fb. LOL) anyway. very long comment. i just wanna say thank you s omuch. sorry for late comment

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  29. is the polarity of photodiode is correct in the circuit diagram??????

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    Replies
    1. yes, Photodiodes are made to use in Reverse bias condition

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  30. Will it be possible to use the L298 motor driver in place of the L293D motor driver?

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    Replies
    1. yes you can use L298 but its connections may vary

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  31. yes sir this is very useful but please be in detail for the next time please just for the sake of beginners...!!!

    ReplyDelete
  32. Hi!
    i am a school student, i liked your project very much,and i would like to use a hc-sr04 sensor mounted on a microservo. what changes should i do? Thanking You.

    ReplyDelete
  33. actually i am doing this project.on my own i have written codes but micro controller didn't get the input from sensor and executes the default case of my prog.i am using mikroc complier.do u have any suggesions regarding my prob.pls help me

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  34. on my own i have written codes . microcontroller doesn't accept input from sensor and drives the motor with default condition(specified in program) . i am using mikroc compiler.are u having any suggession regarding my problem ? pls help me if so

    ReplyDelete