For the outer structure I used aluminum sheet to cover the the robot. In fusion 360 design, I measure the center to center distance between the bases to enter them in the in this wonderful website used to create the cone geometry I need and to output the sheets for the fabrication, it will create a cone with truncated.

Next,I need to enter the bases dimeters. Then I saved the files as PDF to prepare them for the fabrication.

Bottom Cover (cone):

• Top Diameter= 470.624 mm - Base#3
• Bottom Dimeter= 600 mm - Chassis
• Height= 907 mm

Top Cover (Cone):

• Top Diameter= 400 mm - Base#4
• Bottom Dimeter= 470.624 mm - Base#3
• Height= 249.10 mm

At first, I planned to mill them with shopBot, but there wasn’t enough time, So we outsource the cutting of the sheets using a laser cutter as shown below in the video:

Aluminum sheets

Now is time to pleat and assemble the sheets around the inner structure, by using power 😁, Also for the outer structure assembling, I got help from Ali Many Thanks to his great efforts.

Needed equipment:

• Drill.
• 3 mm Aluminum Drilling bit.
• Safety glove.
• Screws.

The process of assembling was to pleat the sheet first around the structure. we must hold it very well, then we label the screws places and start drilling while Ali was drilling I had to hold the sheets very well. Moreover, we had to were gloves because the ends of the aluminum sheets were so sharp.

Details!

I used black screws. so I used silver paint to hide the black dots.

3. Supports:

Having stable structure is very important, so I had to design and 3D printing some supports for the motor holder, and stands. Also the electronics box was 3D printed.

4. Others parts:

Additionally, the Tablet holder and its support was milled with the shopBot. the material of the holder was plywood, but for the Tablet holder support I used HDPE which is very strong which can hold a high load. Moreover, the settings of creating tool-paths for milling HDPE in shopBot is shown below:

Milling Tablet holder support

Moreover, I used a laser cutter, to cut clear Acrylic 10 mm to place the LED Strip on it to give the robot a beautiful appearance. Also to cover the robot from the top I did cut a circle with matt 3 mm Acrylic, and, I used the same Acrylic to cover the plywood in the tablet holder.

Laser cutting!

Wheels Design:

I designed the wheel to be joined to the motor by press-fit the rim into the gearbox of the motor. The wheel design depends on the gearbox used with the motor. As shown below the image of the Electric Reducer Gear Box with DC Motor I used:

The wheel design and fabrication weren’t direct, I had to do several designs and fabrication trials until I came with the best wheel result all the trials will be mention in the Trials and error section.

Rim:

Rim Design

First, I designed the rim to hold the trie, I started by measuring the dimension of the gearbox. Moreover, I found the datasheet of the motor so it was better to get the dimension from it to get the exact shape of the gearbox.

As shown below the final rim design. from the back there is a place to attach the wheel to the gearbox, and, M12 screw bolt will be inserted inside the hole to secure the wheel with the motor from the other side. Additionally, form the front I added some holes in the rim, to make it lighter.

3D printing Rim:

Rim fabrication was direct I used PLA material, also I added support for the printing. However, the printing took a lot of time. One ring needs ~ 10 hours to finish.

Tire:

Tire Design

The Tires design is too simple as shown above with a lines pattern on it. To make the Tires more functional and to increase the friction with the ground to have smooth movement.

3D printing Tire:

For the Tire the fabrication process was not direct. I had to use a flexible material for printing. So the printing settings were a little tricky. Moreover, printing flexible material needs some accuracy and patience.

Printing settings:

• Used filament: colorfabb NGEN_FLEX filament

• I used this link to apply the below settings:

3D printing Tires

Also for the tires, it took around 10 hours to print one tire.

Tire

Tire testing 🤓✌️

As shown below the final wheel design:

Wheel assembling

Final wheels

Tracks:

I used a vinyl cutter for cutting the robot tracks,. I drew the lines with the needed width on CorelDraw. Moreover, the sticker type must be matt. Otherwise, the sensor will not detect the line.

Cutting the Tracks

As shown below in the image the arena I made to test the robot in the Lab.

Electronics Design & Production

Main Board:

For the main control board, I used the ATemga 328p board produced at electronics design week There were all the input and output pins and controlling features I need in this board, Thus I didn’t have to mill and design another one.

PCB Board

Line following sensor:

The line following sensor used to detect a black surface on a white or light surface depending on the contrast.

Its usually pairs IR sensor arrays consists of individual IR LEDs (Transmitter) and IR photodiodes (Receiver).

The IR light emitted by the LED hit the surface and is reflected back to the IR photodiode.

The photodiode then gives an output voltage proportional to the reflectance of the surface.

• High value 1: White surface.

• Low value 0: Black surface.

1. PCB design:

For PCB design I used this video as reference for the line following sensor array design.

Moreover, I watched and used this YouTube playlist which is about robotics a lot in my project, its helped me a lot in building and programming my robot.

His channel name called Arafa Microsys he has a lot of wonderful courses with simple and easy explanations.

The design consists of 4 pairs of IR LED and Photodiode connected on parallel, then the output will give as the values after detecting the surface White or black.

The distance between the IR LED and Photodiode is not random it depend on the tracks width. I set the distance between each pairs ~ 30 mm as shown in the layout. I used the measure tool in eagle.

Thus, the width of the tracks must be >30 mmif I want the robot to move forward when detecting the white surface. Consequently, the width of the track depends on the code.

Components:

Qty	Description
4	Photodiode LED
4	IR LED
4	10 K ohm Resistor
4	100 ohm Resistor
1	2x3 male Header
1	LED

Schematic

Layout

PCB

Soldering

System integration

1. First, connect the DC motors to the L298N H-Bridge board.

2. Then, connect L298N H-Bridge board to my ATemga 328p board:

The table below shows the connection pins between the boards:

L298N H-Bridge board pins	ATemga 328p board pins
IN1	PB1
IN2	PB2
IN3	PB3(MOSI)
IN4	PB0
ENA	PD5
ENB	PD6

I used the the above Circuit Schematic as reference for the connections, but with taking into consideration the pins I have in my board.

3. Next, connect Line following sensor to the ATemga 328P board.

The table below shows the connection pins between the boards:

Line following sensor	ATemga 328p board pins
S1	PC0
S2	PC1
S3	PC2
S4	PD7

4. LED strip is connected direct to 5V power.

5. I used 12v Rechargeable lithium ion battery.

As shown below a rough connection diagram for the system. This not the best connection diagram as its so messy😇😊. However, I did the connections quickly on the diagram to simplifies the system.

Programming, System testing , and, Controlling

Before integrates all system parts together, I had test each one separately. First I started with the line following sensor, then I tested the motors. Next, I connected them together on one board and start to program the robot to follow the line, and, disunite between different intersection points, finally, I will develop an application to make wireless communication between the robot and the app using Bluetooth.

1. line following sensor:

Line Tracking Test Code reference:

//#define center 8     //SS3
#define left A1       //ss2
#define right A2      //ss4
#define extleft A0    //ss1
#define extright 7  //ss5
int c,l,r,el,er;//Define variables which used to store digital inputs values
void setup() {
  Serial.begin(9600);
// pinMode(center,INPUT);
  pinMode(left,INPUT);
  pinMode(right,INPUT);
  pinMode(extleft,INPUT);
  pinMode(extright,INPUT);

}

void loop() {
  el=digitalRead(extleft);
  l=digitalRead(left);
  //c=digitalRead(center);
  r=digitalRead(right);
  er=digitalRead(extright);
  Serial.print(el);
  Serial.print("   ");
  Serial.print(l);
  Serial.print("   ");
  //Serial.print(c);
  //Serial.print("   ");
  Serial.print(r);
  Serial.print("   ");
  Serial.print(er);
  Serial.println();
}

The output signal of the sensor array shown in the serial monitor is either 0 or 1. Moreover, the LED starts working indicating there is power in the board.

• 0 mean black surface.

• 1 mean white surface.

2. Motors.

Test the DC motors with L298N Dual H-Bridge motor drive code reference:

#define in1 2
#define in2 4
#define in3 7
#define in4 8
#define ena 5
#define enb 6

int i=1; //counter for change speed
void setup()
{
  pinMode(in1,OUTPUT);
  pinMode(in2,OUTPUT);
  pinMode(in3,OUTPUT);
  pinMode(in4,OUTPUT);
  pinMode(ena,OUTPUT);
  pinMode(enb,OUTPUT);

}

void loop()
{
  speed1();
  forward();
  delay(5000);
  reverse();
  delay(5000);
  Tright();
  delay(5000);
  Tleft();
  delay(5000);
  off();
  delay(5000);
}
void forward()
{
  digitalWrite(in1,LOW);
  digitalWrite(in2,HIGH);
  digitalWrite(in3,LOW);
  digitalWrite(in4,HIGH);
}

void reverse()
{
  digitalWrite(in1,HIGH);
  digitalWrite(in2,LOW);
  digitalWrite(in3,HIGH);
  digitalWrite(in4,LOW);
}

void Tleft()
{
  digitalWrite(in1,LOW);
  digitalWrite(in2,HIGH);
  digitalWrite(in3,HIGH);
  digitalWrite(in4,LOW);
}

void Tright()
{
  digitalWrite(in1,HIGH);
  digitalWrite(in2,LOW);
  digitalWrite(in3,LOW);
  digitalWrite(in4,HIGH);
}

void off()
{
  digitalWrite(in1,LOW);
  digitalWrite(in2,LOW);
  digitalWrite(in3,LOW);
  digitalWrite(in4,LOW);
}

void speed1()
{
  if(i==5) i=1;
  analogWrite(ena,255);
  analogWrite(enb,255);
  i++;

}

As shown below on the video, this code responsible to move the robot, forward, reverse, turning right, and, turning left. I had to change the speed used in the reference code because each motor differs from the other. The movement of the motors depends a lot on the speed and supplied voltage.

3. Turn Testing Code:

After I make sure the motor drive works well with the motors I have. Now it’s the time to test the robot turning and movement.

The movement and rotation of motors depend on:

1. Motors - each motor differs and needs to be tested to know which code will do so.

2. Weight - It depends on the weight the robot carries because the weight will affect the speed and the movement of the robot.

3. Supply voltage - If the supplied voltage change everything in the code will change, So I have to ensure to have the battery full all time, to get accuracy test for the movements.

4. Delay on the code

//Created by Arafa Microsys
//www.youtube.com/arafamicrosystems
// Please, don't trade the code without mentioning the source (Arafa Microsystems http://www.youtube.com/arafamicrosystems )
//So as not waste the effort
#define in1 9 //Right motor pole 1
#define in2 10  //Right motor pole 2
#define in3 11  //left motor pole 1
#define in4 8  //left motor pole 1
#define ena 5  //Right motor speed
#define enb 6  //Right motor speed
//#define center 11     //SS3
#define left A1       //ss2
#define right A2      //ss4
#define extleft A0    //ss1
#define extright 7   //ss5

void setup()
{
  //Serial.begin(115200);
  pinMode(in1,OUTPUT);
  pinMode(in2,OUTPUT);
  pinMode(in3,OUTPUT);
  pinMode(in4,OUTPUT);
  pinMode(ena,OUTPUT);
  pinMode(enb,OUTPUT);
  //pinMode(center,INPUT);
  pinMode(left,INPUT);
  pinMode(right,INPUT);
  pinMode(extleft,INPUT);
  pinMode(extright,INPUT);
  analogWrite(ena,255);
  analogWrite(enb,255);
}

void loop()
{ // Turn Right Test, using the dealy, trial and error until reach 90 degree

//  analogWrite(ena,150);
//  analogWrite(enb,170);
//  
  analogWrite(ena,200);
  analogWrite(enb,200);
  digitalWrite(in1,HIGH);
  digitalWrite(in2,LOW);
  digitalWrite(in3,HIGH);
  digitalWrite(in4,LOW);
   delay(1000);

  delay(10000);
// off the motors
 digitalWrite(in1,LOW);
  digitalWrite(in2,LOW);
  digitalWrite(in3,LOW);
  digitalWrite(in4,LOW);

  delay(2000);


}

As shown below the turning and movement tests I did for the robot, by trial and error the values until I reach to the best result.

4. Full code:

Next, I used the turning test program I did above in this final code were is needed. This code is responsible:

1. Make the robot follow the line.

2. Make the robot Go to the desired location depending on the intersection points and his reference location.

//Created by Arafa Microsys
//www.youtube.com/arafamicrosystems
// Please, don't trade the code without mentioning the source (Arafa Microsystems http://www.youtube.com/arafamicrosystems )
//So as not waste the effort
#define in1 9  //Right motor pole 1
#define in2 10  //Right motor pole 2
#define in3 11 //left motor pole 1
#define in4 8  //left motor pole 1
#define ena 5  //Right motor speed
#define enb 6  //Right motor speed
//#define center 11     //SS3
#define left A1       //ss2
#define right A2      //ss4
#define extleft A0    //ss1
#define extright 7   //ss5
//int prev,time1;
//float timeStep = 0.01;
//float yaw = 0;
int l,r,el,er;//Define variables which used to store digital inputs values
int mask=0,mask2=0,mask3=0,mark1=0,mark2=0;
int x=0,y=0,ox=0,oy=0,nx=0,ny=0,pos=0;
int state=0;//orientation state (1=Forward, 2=Reverse, 3=Right, 4=Left)Zero is initial state
void setup()
{
  //Serial.begin(115200);
  pinMode(in1,OUTPUT);
  pinMode(in2,OUTPUT);
  pinMode(in3,OUTPUT);
  pinMode(in4,OUTPUT);
  pinMode(ena,OUTPUT);
  pinMode(enb,OUTPUT);
  //pinMode(center,INPUT);
  pinMode(left,INPUT);
  pinMode(right,INPUT);
  pinMode(extleft,INPUT);
  pinMode(extright,INPUT);
  analogWrite(ena,100);
  analogWrite(enb,100);
}
void loop()
{
  getxy();
  calc();
}

void inertia()
{
  analogWrite(ena,150);
  analogWrite(enb,150);
  digitalWrite(in1,LOW);
  digitalWrite(in2,HIGH);
  digitalWrite(in3,LOW);
  digitalWrite(in4,HIGH);
  delay(100);
}
void forward()
{
  analogWrite(ena,85);
  analogWrite(enb,85);
  digitalWrite(in1,LOW);
  digitalWrite(in2,HIGH);
  digitalWrite(in3,LOW);
  digitalWrite(in4,HIGH);
  //delay(200);
}

void reverse()
{
  digitalWrite(in1,HIGH);
  digitalWrite(in2,LOW);
  digitalWrite(in3,HIGH);
  digitalWrite(in4,LOW);
}

void Tleft()
{
  analogWrite(ena,130);
  analogWrite(enb,110);
  digitalWrite(in1,LOW);
  digitalWrite(in2,HIGH);
  digitalWrite(in3,HIGH);
  digitalWrite(in4,LOW);
  //delay(100);
}
void Tright()
{
  analogWrite(ena,110);
  analogWrite(enb,130);
  digitalWrite(in1,HIGH);
  digitalWrite(in2,LOW);
  digitalWrite(in3,LOW);
  digitalWrite(in4,HIGH);
  //delay(100);
}
void off()
{
  digitalWrite(in1,LOW);
  digitalWrite(in2,LOW);
  digitalWrite(in3,LOW);
  digitalWrite(in4,LOW);
}
void Tleft90()
{
  analogWrite(ena,170);
  analogWrite(enb,170);
  digitalWrite(in1,LOW);
  digitalWrite(in2,HIGH);
  digitalWrite(in3,HIGH);
  digitalWrite(in4,LOW);
  delay(660);
}
void Tright90()
{
    analogWrite(ena,170);
    analogWrite(enb,150);
    digitalWrite(in1,HIGH);
    digitalWrite(in2,LOW);
    digitalWrite(in3,LOW);
    digitalWrite(in4,HIGH);
    delay(660);
}

void Tleft180()
{
  analogWrite(ena,170);
  analogWrite(enb,170);
  digitalWrite(in1,LOW);
  digitalWrite(in2,HIGH);
  digitalWrite(in3,HIGH);
  digitalWrite(in4,LOW);
  delay(1100);
}

void Tright1()
{
  analogWrite(ena,150);
  analogWrite(enb,150);
  digitalWrite(in1,HIGH);
  digitalWrite(in2,LOW);
  digitalWrite(in3,LOW);
  digitalWrite(in4,HIGH);
  //delay(100);
}

void Tleft1()
{
  analogWrite(ena,150);
  analogWrite(enb,150);
  digitalWrite(in1,LOW);
  digitalWrite(in2,HIGH);
  digitalWrite(in3,HIGH);
  digitalWrite(in4,LOW);
  //delay(100);
}
void getvalues()
{
  // If value is equal to 0 means Black and other 1 means White
  el=digitalRead(extleft);
  l=digitalRead(left);
  //c=digitalRead(center);
  r=digitalRead(right);
  er=digitalRead(extright);

}
void compare()
{
    if(el==1&&l==1&&r==1&&er==1)
  {

    if(mask2==0)
    {
      inertia();
      mask2=1;
    }
    forward();
  }
  if(el==1&&l==0&&r==1&&er==1||el==0&&l==1&&r==1&&er==1)
  {
    Tleft();
  }
  if(el==1&&l==1&&r==0&&er==1||el==1&&l==1&&r==1&&er==0)
  {
    Tright();
  }

  if(el==0&&l==0&&r==0&er==0&&mask==0)
  {
     off();
     delay(100);
     mask=1;
     if(y>0&&x<0&&mark1==1||y<0&&x>0&&mark1==1)
     {
      pos--;
     }
     else if(x<0&&y<0&&mark2==1||y<0&&x==0||x<0&&y==0)
     {
      pos--;
     }else pos++;

    //inertia();
    forward();
  }
  if(el==1&&er==1)
  {
    mask=0;
  }
}
void getxy()
{
  nx=-1;
  ny=-1;
}
void calc()
{
  x=nx-ox;
  y=ny-oy;
  if(x>0&&y>0)
  {
    exy();
    state=3;
    orientation();
    exx();
    state=4;
    orientation();
    while(1)
    {
      off();
    }

  }else if(x<0&&y<0)
  {
    mark2=1;
    getvalues();
    state=2;
    orientation();
    exy1();
    state=3;
    orientation();
    exx1();
    state=3;
    orientation();
    mark2=0;
    while(1)
    {
      off();
    }
  }else if(x==0&&y>0)
  {
    getvalues();
    exy();
    while(1)
    {
      off();
    }
  }else if(x==0&&y<0)
  {
    getvalues();
    state=2;
    orientation();
    exy1();
    state=2;
    orientation();
    while(1)
    {
      off();
    }
  }else if(y==0&&x>0)
  {
    getvalues();
    state=3;
    orientation();
    exx();
    state=4;
    orientation();
    while(1)
    {
      off();
    }
  }else if(y==0&&x<0)
  {
    getvalues();
    state=4;
    orientation();
    exx1();
    state=3;
    orientation();
    while(1)
    {
      off();
    }
  }else if(x>0&&y<0)
  {
    getvalues();
    state=3;
    orientation();
    exx();
    state=3;
    orientation();
    mark1=1;
    exy1();
    state=2;
    orientation();
    mark1=0;
    while(1)
    {
      off();
    }
  }else if(x<0&&y>0)
  {
    getvalues();
    exy();
    state=4;
    orientation();
    mark1=1;
    exx1();
    state=3;
    orientation();
    mark1=0;
    while(1)
    {
      off();
    }
  }

}

void orientation()
{
  if (state==2)
  {//reverse Orientation
    Tleft180();
    off();
    state=0;
  }else if(state==3)
  {
    //inertia();
    Tright90();
    off();
    state=0;
  }else if(state==4)
  {
    inertia();
    Tleft90();
    off();
    state=0;
  }
}

void exy()
{
  loop7:
  if(y>pos)
  {
    getvalues();
    compare();
  }else if(y==pos)
  {
    off();
    pos=0;
    goto loop8;
  }
  goto loop7;
  loop8:
  pos=0;
}

void exx()
{
  loop9:
  if(x>pos)
  {
    getvalues();
    compare();
  }else if(x==pos)
  {
    off();
    pos=0;
    goto loop10;
  }
  goto loop9;
  loop10:
  pos=0;
}

void exy1()
{
  loop7:
  if(y<pos)
  {
    getvalues();
    compare();
  }else if(y==pos)
  {
    off();
    pos=0;
    goto loop8;
  }
  goto loop7;
  loop8:
  pos=0;
}

void exx1()
{
  loop9:
  if(x<pos)
  {
    getvalues();
    compare();
  }else if(x==pos)
  {
    off();
    pos=0;
    goto loop10;
  }
  goto loop9;
  loop10:
  pos=0;
}

Final code test video:

5. First line Following using different code:

I was struggling to make the robot to follow the track, with the above code so I tried a different code, and it worked. But still not following the line properly as shown in the video below. He goes in/out of the path, and sometimes he follow the line and sometimes he didnt. I planning to improve the code by using PID control to ensure the stabilty of the robot while following.

/*Mert Arduino and Raspberry Pi - Line Following Robot*/

//Define Pins

int ENA = 5; //Enable Pin of the Right Motor (must be PWM)
int IN1 = 9; //Control Pin
int IN2 = 10;

int ENB = 6; //Enable Pin of the Left Motor (must be PWM)
int IN3 = 11;
int IN4 = 8;

//Speed of the Motors
#define ENASpeed 150
#define ENBSpeed 120

int Sensor1 = 0;
int Sensor2 = 0;
int Sensor3 = 0;
int Sensor4 = 0;

void setup() {

  pinMode(ENA, OUTPUT);
  pinMode(IN1, OUTPUT);
  pinMode(IN2, OUTPUT);

  pinMode(ENB, OUTPUT);
  pinMode(IN3, OUTPUT);
  pinMode(IN4, OUTPUT);

  pinMode(Sensor1, INPUT);
  pinMode(Sensor2, INPUT);
  pinMode(Sensor3, INPUT);
  pinMode(Sensor4, INPUT);

}

void loop(){

  //Use analogWrite to run motor at adjusted speed
  analogWrite(ENA, ENASpeed);
  analogWrite(ENB, ENBSpeed);

  //Read the Sensor if HIGH (BLACK Line) or LOW (WHITE Line)
  Sensor1 = digitalRead(A0);
  Sensor2 = digitalRead(A1);
  Sensor3 = digitalRead(A2);
  Sensor4 = digitalRead(7);

  //Set conditions for FORWARD, LEFT and RIGHT

  if(Sensor4 == HIGH && Sensor3 == HIGH && Sensor2 == LOW && Sensor1 == LOW){

    //Turn LEFT
    //motor A Backward
    digitalWrite(IN1, LOW);
    digitalWrite(IN2, HIGH);

    //motor B Forward
    digitalWrite(IN3, HIGH);
    digitalWrite(IN4, LOW);
  }

  else if (Sensor4 == LOW && Sensor3 == LOW && Sensor2 == HIGH && Sensor1 == HIGH){

    //Turn RIGHT
    //motor A Forward
    digitalWrite(IN1, HIGH);
    digitalWrite(IN2, LOW);

    //motor B Backward
    digitalWrite(IN3, LOW);
    digitalWrite(IN4, HIGH);
  }

  else{

    //if(Sensor4 == LOW && Sensor3 == HIGH && Sensor2 == HIGH && Sensor1 == LOW

    //FORWARD
    digitalWrite(IN1, HIGH);
    digitalWrite(IN2, LOW);
    digitalWrite(IN3, HIGH);
    digitalWrite(IN4, LOW);
  }
}

Results and discussion:

I had noticed whenever the battery not fully charge or when I tested with chassis or with the entire body I get different results. So, in the future, I plan to test the robot with a better battery with high capacity and longer charging time of the battery. Moreover, the testing must be with all robot parts so the weight will not affect the code. The robot follows the line, what left is to make him define the different intersection points and connect him with the app to control him.

Application

Steps:

• Create Account on MIT App Inventor.

• Download MIT app in the Tablet.

• Connect the application with the tablet through Bluetooth.

• The app is ready to use.

Testing bluetooth model:

• I watched some YouTube Videos to start with the MIT Inventor website, then I open and start a new project and developed the application. Before I start making my own App for the robot, I Tested bluetooth model with creating an basic app to turn the LED on/off.

As shown in the video below:

Code:

#include <softwareserial.h>


SoftwareSerial BT(10, 11); //TX, RX respetively
String state;// string to store incoming message from bluetooth


void setup() {
 BT.begin(9600);// bluetooth serial communication will happen on pin 10 and 11
 Serial.begin(9600); // serial communication to check the data on serial monitor
  pinMode(13, OUTPUT); // LED connected to 13th pin




}
//-----------------------------------------------------------------------//  
void loop() {
  while (BT.available()){  //Check if there is an available byte to read
  delay(10); //Delay added to make thing stable
  char c = BT.read(); //Conduct a serial read
  state += c; //build the string- either "On" or "off"
  }  
  if (state.length() > 0) {
    Serial.println(state);


  if(state == "turn on")
  {
    digitalWrite(13, HIGH);

      }

  else if(state == "turn off")
  {
    digitalWrite(13, LOW);
     }


state ="";}} //Reset the variable


</softwareserial.h>

Developing user interface:

As shown from the below images and video, I had finish develop the first user interface design. what left is connect each button of the app to the robot.

First to start and operate the robot press the start guide tour button. This button responsible to turn on the robot.

Second, as shown there are two choices: To have a full guide tour of the lab: the robot will demonstrate the entire Fablab for the visitors and explains all the actives. this section is still under development. The second choice is to select a room for you are interested to know her actives. Finally, press on back to take the robot back to his home point which is Fablab reception.

Application Video

Final Product