University of Nevada Las Vegas

Mechatronics Tutorial

(version 1)

By

Makram Abd El Qader

Charbel azzi

Jonathan Burgos

Nirup Nirvan

30 June 2009

Mechatranocis Tutorial

1. Introduction

2. Motivation

3. Learning Objectives

4. Safety Issues

5. machine shop and Tools

6. Project phase

6.1 Phase one- Fully controlled mini-car with infrared sensing on board.

6.2 Phase two- Phase One plus ultrasonic and temperature sensors on board.

6.3 Phase three- Phase One, Phase Two plus wireless controlled mini-car

7. Mechanical Design & Implementation

7.1 Project Components

7.1.1 Gear Box kit

7.1.2 Dc Motors

7.1.3 Tires

7.1.4 Plat Form Holder

7.2 Implementation

7.2.1 Gear Box DesigN

7.2.2 Setting the tires up

7.2.3 Connecting the Motors

8. Electrical Design & Implementation

8.1 Project Components

8.1.1 Microcontroller

8.1.1.1 General Background

8.1.1.2 Why do we use a Microcontroller?

8.1.1.3 Why using Adruino Microcontroller?

8.1.1.4 Applications

8.1.1.5 Programming examples

8.1.2 Motor Driver

8.1.3 RC Battery

8.1.4 Sensors

8.1.4.1 Infrared Sensor

8.1.4.2 Temperature Sensor

8.1.4.3 Ultrasonic Sensor

8.1.5 PCB-Printed Circuitry Board

8.2 Implementation

8.2.1 Driver Connections

8.2.2 Sensors Connections

8.2.3 Programming the microcontroller using Adruino software( c++ based)

9. Mechatronics Final Design

10. Cost

11. Conclusion

12. Sponsors

13. Acknowledgments

14. References

1. Introduction

Mechatronics is the synergistic combination of mechanical engineering, electronic

engineering, control engineering, systems design engineering, and computer engineering

to create useful products. One of the purposes of this interdisciplinary engineering field is

the study of automata from an engineering perspective and serves the purposes of

controlling advanced hybrid electro mechanical systems. The word itself is a combination

of 'Mechanics' and 'Electronics'. The importance of multi-disciplinary engineering

projects has increased along with the accelerated rate of technological advancement

industry-wide. Because all areas of technology are advancing, effective design of a single

product often requires close integration of a wide range of disciplines. Microprocessors

and sensors have become pervasive within many engineering products, and mechanical

engineers will often interface with electrical engineers or select and implement electronic

components themselves.

The mechatronics design project has specifically been selected as it is multi-disciplinary

and is based on microprocessor. The project encompasses multiple sub-disciplines of

engineering and computer science.

· Mechanical structure

· Dynamics

· Motor performance

· Motor Driver performance

· Sensor performance

· Control Algorithm

· Real-time software implementation

2. Motivation

This project is intended for hands-on education and training for undergraduate

engineering students. The structure of the project allows instructors to use material in a

modular fashion. Additional modular projects can be easily built around this project to

teach students asynchronously at freshman, sophomore, junior, or senior levels. This

project covers fundamental topics from electrical engineering, computer engineering and

mechanical engineering.

3. Learning Objectives

Student will learn:

1. To analyze and design a DC circuits ( power, capacitors, resistors, and

wiring)

2. To understand sensors, their applications and implemetation ( infrared

sensor, temperature sensor, ultrasonic sensor)

3. To use and implement microcontrollers (Adruino development board with

ATMEGA 328) and programming- Control algorithm- Real-time software

4. To use soldering of electrical components on PCB (soldering tools and

hands on experience)

5. To understand power consumption by electrical device (RC batteries and

charging concept)

6. To incorporate DC motors and motor driver- H bridge in the design for

specific application ( DC motors functions and specifications)

7. To use electrical testing equipments such as (voltmeter, oscilloscope,

function generator, and power supply etc…..)

8. To familiarize oneself with gear box kit and its assembly.

9. To understand and use gear ratio, Power train selection (belt, gear, etc.),

Bearings and shafts

10. To familiarize oneself Get familiar to use solid works software for

mechanical design

11. To design strength issues in mechanical design.

4. Safety issues

All the students must attend a safety seminar offered by the Mendenhall lab instructor.

5. Machine shop and Tools

Students are required to do their research and project assembly in the laboratory space

assigned for this project under the supervision of the lab instructor. Students will have

access to the machine shop and electronic shop associated with Mendenhall center.

The machine shop is located in room #TBE B200 and the electronic shop in room #

TBE B. Students must undergo an equipment usage and safety seminar for the

machinery shop and the electronic shop before getting access.

6. Project phase

The project is designed in a a modular fashion with three phases.

6.1 Phase one- Fully controlled mini-car with infrared sensing on board.

Using an infrared sensor would have many different applications on

our mini car. For example we could program it in way that it

Would avoid encountered walls (as we will see in the microcontroller

Section ).

6.2 Phase two- Phase One plus ultrasonic and temperature sensors on board.

In this phase and for more sensor precision we implemented an

ultrasonic sensor that will allow us to have a bigger range. Moreover

we introduced temperature sensor around our car. The temperature

sensor are not only for getting the room temperature, but we also used the

for another application. For example, our mini car would be able to follow

the heat.

6.3 Phase three- Phase One, Phase Two plus wireless controlled mini-car

In the previous phases we were uploading the program into our

microcontroller in order to control our car. Now we will be able to control

our car wirelessly.

7. Mechanical Design

7.1 project components

7.1.1 Gearbox and torque explanation

Parts to the gearbox

Fig.1. Gearbox parts & DC Motors

1- 2 DC motors

2- 2 wheels and 2 tires

3- 4 axles shaft

4- 8 gears

5- 2 nuts with fit screws

6- 4 screws

7- 2 washers

8- 2 plastic sides pieces and 1 middle piece (gear box covers)

Gear box and motors

First thing is to understand how a gearbox works. In order to rotate gears we need

a torque. What’s Torque?

Fig.2. Torque and forces

Torque: measure of a force's tendency to produce rotation When the force is applied at

a farther distance from the center of rotation, it is easier to produce rotation. Torque is

the product of the force and the distance from the point application of the force and the

center of rotation. (Note: the force and the length ‘vector” is perpendicular to each

other). From the figure: Fλ1>F λ2

Why We Need Gearsbox?

Fig.3. Gearbox fully assembled

DC motors have high speed but no torque. For example if we use the DC motors

and directly connect to the wheels. The wheels will not have enough power to move up a

hill or even on flat floor because of the friction force to overcome is greater > than torque

that the DC motor produces.

Fig.4. Tires

Fig.5.inside the gearbox

Use gears so that the low torque and high speed at the motor shaft is transferred to wheel

as high torque/low speed. The high torque at the wheel can counter the ground friction so

that now the wheels move when they are put on the ground.

Fig.6. Greater the voltage applied to the motor, higher its angular speed.

7.1.2 Dc Motors

Motors come in many sizes and types, but their basic function is the same. Motors of all

types serve to convert electrical energy into mechanical energy. They can be found in

VCR's, elevators, CD players, toys, robots, watches, automobiles, subway trains, fans,

space ships, air conditioners, refrigerators, and many other places. D.C. motors as shown

in Fig.7 are motors that run on Direct Current from a battery or D.C. power supply.

Direct Current is the term used to describe electricity at a constant voltage. A.C. motors

run on alternating Current, which oscillates with a fixed cycle between a positive and

negative value. Electrical outlets provide A.C. power. When a battery or D.C. power

supply is connected between a D.C. motor's electrical leads, the motor converts electrical

energy to mechanical work as the output shaft turns.

Fig.7. Dc Motor

Dc Motors functioning is characterized by Lorentz Force Law:

F = I x B

Where:

F = force on wire

I = current

B = magnetic field

Which work on the concept of the Right hand rule:

Index finger along I,

Middle finger along B,

Thumb along F

The physics behind the Dc Motors is shown in the figure below:

Fig.8. Dc Motor function

N S

In order to effectively design with D.C. motors, it is necessary to understand their

characteristic curves. For every motor, there is a specific Torque/Speed curve and Power

curve as shown in Fig 9.

.

Fig.9. Dc motor Torque/Speed curve and Power curve

The graph above shows a torque/speed curve of a typical D.C. motor. Note that torque is

inversely proportional to the speed of the output shaft. In other words, there is a tradeoff

between how much torque a motor delivers, and how fast the output shaft spins. Motor

characteristics are frequently given as two points on this graph:

The stall torque, , represents the point on the graph at which the torque is a

maximum, but the shaft is not rotating.

The no load speed, , is the maximum output speed of the motor (when no

torque is applied to the output shaft).

The curve is then approximated by connecting these two points with a line, whose

equation can be written in terms of torque or angular velocity as equations 3) and 4):

Dc Motors will be studies further more in EE340 power and transmition lines class.

7.1.3 Plat Form Holder

We designed a plate of width 2.23 inches, and of length 6.5 inches (the length of the plate

could be as much as you need to place all the components that you need). We placed the

batteries, the circuit board and the microcontroller on top of the plate and the gear box at

the bottom. We made two whole of 1/8 of an inch in order to fix the gear box to the

bottom of the plate. Since we’re still in the testing phase we used a double sided metal

scotch to place the components on the plate instead of screwing them.

7.2 Mechanical Design Implementation

7.2.1 Gearbox design and assembly

Step 1

Fig.10.gears

1. Set the gears up like figure 10 above connected with the middle plastic piece.

2. Place the nut with the fit screw on the gear with shape of nut and then tighten it

the shaft as fig 11 Make sure you place a bearing/washer in slot where the axle is

inserted to the plastic piece.

3. Insert the 2 screws. Don’t over tighten screws.

4. Place the DC motor in slot like the figure below.

5. Repeat step 1 for other side.

Fig.11. gears and motor

Step 2

1. Attach the wheels to the end of the shaft. Refer to figure 10 below.

Fig.12. geras, motor and wheeels

8. Electrical Design

8.1 Project components

8.1.1 Microcontroller:

8.1.1.1General background:

A microcontroller is a small computer on a single integrated circuit, where

micro stands for small and controller means that this single chip is able to

control external devices. Microcontroller is similar to a personal computer

(PC). They both have a central processing unit (CPU), where the entire

math, the logic, and the data-moving are done. The only two differences is

that first the microcontroller is a single chip that contain the memory and

the I/O (input/output like keyboards, monitors, speakers, etc...), while in a

complete computer the memory and the I/O are not on a single-chip.

Second, the memory and interface (e.g. I/O) in a microcontroller are p

limited comparing to a complete computer.

8.1.1.1Why as designers we use a microcontroller?

We use a microcontroller in order to:

Input information from different external devices (e.g. sensors,

keyboards)

Analyze these inputs and use them in set of actions according to our

need.

Use the output mechanisms on the Microcontroller to do something

useful(e.g. run and turn off a motor)

8.1.1.2Why using an Adruino microcontroller?

Most microcontrollers could be only used with windows while the

Adruino software runs n Macintosh OSX, and Linux operating

systems.

Adruino is simpler than other microcontrollers to be programmed by

beginners, and yet flexible for advanced users. The Adruino Software

could be extended by advanced programmers, and can be expanded

through the C++ libraries.

8.1.1.3Applications:

Microcontrollers in general have many applications. Any project or object

that requires memory, and control system could be an application for any

microcontroller.

For example:

Wall avoiding robot, it avoids a wall when encountered. Avoiding the

wall could be by moving in different direction when a wall

encountered or even by turning around it.

Know how the weather is like outside. This could be done by

connecting our microcontroller to a humidity and temperature sensors

that are placed outside.

RC Car Controlled Via the Web: Strap on a standard Linksys router to

an RC car and you can wirelessly control it through the web from up to

1640 feet away.

8.1.1.4Programming examples:

a- Download the Adruino software from http://arduino.cc/en/Main/Software

The figure below shows the Adruino microcontroller that we’re using.

Fig.12. Adruino microcontroller Board

b- Work with some simple examples :

Digital I/O (e.g. blinking LED’s with, without delays, and controlling)

Analog I/O (use a potentiometer to control the blinking of an LED and

calibration for analog sensor readings)

8.1.2Motor driver

An H-bridge is an electronic circuit which enables a voltage to be applied across a load in

either direction. These circuits are often used in robotics and other applications to allow

DC motors to run forwards and backwards. H-bridges are available as integrated circuits,

or can be built from discrete components. Fig.13 illistrates the motor driver functions.

Fig.13. Structure of an H-bridge

This configuration is called an H-Bridge due to its shape. Let's say that the motor runs

forward when its + terminal is connected to Motor V+ and its - terminal is connected to

ground. It will run in reverse when the opposite is true. Turn on switch A and switch D

and the motor will run forward. Turn on switch B and switch C and it will run in reverse.

The following table shows all of the possibilities. A 1 means a switch is on, and a 0

means it's off:

A B C D State A B C D State

0 0 0 0 Off 1 0 0 0 Off

0 0 0 1 Off 1 0 0 1 Forward

0 0 1 0 Off 1 0 1 0 SHORT!!

0 0 1 1 Brake 1 0 1 1 SHORT!!

0 1 0 0 Off 1 1 0 0 Brake

0 1 0 1 SHORT!! 1 1 0 1 SHORT!!

0 1 1 0 Reverse 1 1 1 0 SHORT!!

0 1 1 1 SHORT!! 1 1 1 1 SHORT!!

Table.1. H- bridge truth table

In our project we will be using the L293D IC motor driver as shown in Fig.14. The

L293D is quadruple high-current half-H drivers. The L293D is designed to provide bidirectional

drive currents of up to 600-mA at voltages from 4.5 V to 36 V. The device is designed to drive

inductive loads such as relays, solenoids, dc and bipolar stepping motors.

Fig.14. L293D IC chip

8.1.3 RC Battery:

Fig.15. RC battety

8.1.4 Sensors:

A sensor is a device that measures a physical quantity and converts it into a signal which

can be read by an observer or by an instrument. A good sensor obeys the following rules:

Is sensitive to the measured property

Is insensitive to any other property

Does not influence the measured property

Ideal sensors are designed to be linear. The output signal of such a sensor is linearly

proportional to the value of the measured property. The sensitivity is then defined as the

ratio between output signal and measured property. For example, if a sensor measures

temperature and has a voltage output, the sensitivity is a constant with the unit [V/K]; this

sensor is linear because the ratio is constant at all points of measurement. There is a wild

vairety of sensors that could be used for many application, such as temperatue sensors,

infrared sensors, ultrasonic sensors,optical sensors, chemical and biological sensors,etc.. .

8.1.4.1Infrared sensor

Infrared sensor is an electronic device that measures infrared (IR) light radiating from

objects in its field of view. Because it does not emit any energy, its often mistakenly

called a Passive Infrared Sensor. PIR sensors are often used in the construction of PIR-

based motion detectors (see below). Apparent motion is detected when an infrared source

with one temperature, such as a human, passes in front of an infrared source with another

temperature, such as a wall. All objects emit what is known as black body radiation. It is

usually infrared radiation that is invisible to the human eye but can be detected by

electronic devices designed for such a purpose. The term passive in this instance means

that the PIR device does not emit an infrared beam but merely passively accepts

incoming infrared radiation.

In this project we will be using the following infrared sensor:

Part Number: R146-GP2D120

Price: $12.50

Weight: 0.04 lbs

This sensor takes a continuous distance reading and returns a corresponding analog

voltage with a range of 4cm (1.6") to 30cm (12").

Fig.16 infrared sensor

Absolute Maximum Ratings

Parameter Symbol Rating Unit Remarks

Supply Voltage VCC -0.3 to +7 V

Output Terminal Voltage VO -0.3 to VCC+0.3 V

Operating Temp. Topr -10 to +60 °C

Storage Temp. Tstg -40 to +70 °C

Operating Supply Voltage

Parameter Symbol Rating Unit Remark

Operating Supply Voltage VCC 4.5 to 5.5 V

Electro-Optical Characteristics

Parameter Symbol Conditions Min. Typ. Max. Unit

Measuring distance

range delta L *1 4 - 30 cm

Output Terminal

Voltage VO L = 30 cm *1 0.25 0.4 0.55 V

Output voltage

difference

delta

VO

Output change at L change (30 cm

-> 4 cm) *1 1.95 2.25 2.25 V

Average supply

current Icc L = 30 cm, *1 - 33 50 mA

L: Distance to reflected object *1 Using reflected object: White paper (Made by Kodak Co. Ltd. gray cards

R-27, white face, reflective ratio: 90%)

8.1.4.2 Temperature sensor

Thermistors are inexpensive, easily-obtainable temperature sensors. They are easy to use

and adaptable. Circuits with thermistors can have reasonable outout voltages - not the

millivolt outputs thermocouples have. Because of these qualities, thermistors are widely

used for simple temperature measurements. They're not used for high temperatures, but

in the temperature ranges where they work they are widely used.

Thermistors are temperature sensitive resistors. All resistors vary with temperature, but

thermistors are constructed of semiconductor material with a resistivity that is especially

sensitive to temperature. However, unlike most other resistive devices, the resistance of a

thermistor decreases with increasing temperature. That's due to the properties of the

semiconductor material that the thermistor is made from. For some, that may be

counterintuitive, but it is correct. Here is a graph of resistance as a function of

temperature for a typical thermistor. Notice how the resistance drops from 100 kW, to a

very small value in a range around room temperature. Not only is the resistance change

in the opposite direction from what you expect, but the magnitude of the percentage

resistance change is substantial.

Fig.17. resistant – Temperature relation

In this lesson you will examine some of the characteristics of thermistors and the

circuits they are used in.

Why Use Thermistors To Measure Temperature?

o They are inexpensive, rugged and reliable.

o They respond quickly

In this project we will be using the LM34CZ Temperature Sensor which

produces an output voltage proportional to the current measured temperature. The

LM34CZ comes in a TO-92 plastic package and has range of -40F to +230F.

Fig.18. LM34CZ Temp. sensor

8.1.4.3Ultrasonic sensor

Ultrasonic sensors or transducers when they both send and receive work on a principle

similar to radar or sonar which evaluate attributes of a target by interpreting the echoes

from radio or sound waves respectively. Ultrasonic sensors generate high frequency

sound waves and evaluate the echo which is received back by the sensor. Sensors

calculate the time interval between sending the signal and receiving the echo to determine

the distance to an object as shown in fig.19.

Fig.19.ultrasonic sensor wave sketch

In this project we will be using the PING Ultrasonic Sensor fig.20 which provides a very

low-cost and easy method of distance measurement. This sensor is perfect for any

number of applications that require you to perform measurements between moving or

stationary objects. Naturally, robotics applications are very popular but you'll also find

this product to be useful in security systems or as an infrared replacement if so desired.

You will definitely appreciate the activity status LED and the economic use of just 1 I/O

pin.

Fig.20. PING Ultrasonic Sensor

PING)))™ Sensor Features

The PING))) has only has 3 connections, which include Vdd, Vss, and 1 I/O pin.

The 3-pin header makes it easy to connect using a servo extension cable, no

soldering required.

Several sample codes are available using the Ping))) sensor.

Key Specifications:

Range - 2cm to 3m (~.75" to 10')

Supply Voltage: 5V +/-10% (Absolute: Minimum 4.5V, Maximum 6V)

Supply Current: 30 mA typ; 35 mA max

3-pin interface (power, ground, signal)

20 mA power consumption

Narrow acceptance angle

Simple pulse in / pulse out communication

Indicator LED shows measurement in progress

Input Trigger - positive TTL pulse, 2 µs min, 5 µs typ.

Echo Pulse - positive TTL pulse, 115 µs to 18.5 ms

Echo Hold-off - 750 µs from fall of Trigger pulse

Burst Frequency - 40 kHz for 200 µs

Size - 22 mm H x 46 mm W x 16 mm D (0.85 in x 1.8 in x 0.6 in)

To learn more about the sensor application and schematics you can check out the

documentation from the following website http://www.parallax.com/.

8.1.5 PCB-Printed Circuitry Board

A printed circuit board, or PCB, is used to mechanically support and electrically connect

electronic components using conductive pathways, or traces, etched from copper sheets

laminated onto a non-conductive substrate as shown in fig 21.

Fig.21. PCB

In designing PCB the student must have full knowledge with Ultimatum software, which

is a tool to help generate a PCB schematic and final design of project circuit. However in

the current project we will be using a complete PCB that will fit all our circuitry

components as shown in fig22.

Fig.22. PCB ready for usage

In the time of PCB usage, student must have taken an introduction and safety seminar

on soldering of integrated circuit-IC components as mention in section 3.

8.2 electrical Design Implementation

8.2.1 Driver Connection

Connecting the microcontroller to the driver and run the motors:

As we mentioned before the microcontroller is usually helpful when we

receive some kind of inputs from externals devices and then outputs some

actions according to these inputs. However, now we don’t need any inputs

to the microcontroller since at this phase we’re only concerned about

turning on the motors.

In this phase we will send a signal from the microcontroller to the driver that will

turn one or the two motors on depending on our code.

In order to do that, we need to first to take care of the electrical part before start

programming it. Therefore, we connected pin 2 and pin 7 of the driver to the

digital pins of the Adruino 7 & 8 respectively, and pin 15 and 10 of the driver to

the digital pins 2 and 4 respectively (fig23 ). Notice that so far we connected the

microcontroller to the driver but not yet to the motor. In order to do that we will

connect pin 3 and 6 of the driver to the motor A, and pin 14 and 11 to the motor B

(fig 23).

Fig.23. the figure above is a simple motor driver circuit using the L293D

Motor driver

Like any driver the L293D need a power and a ground. As we see in fig23 the

pins 1, 8, 9 and 16 are the power pins, and 4, 5, 12, and 13 are the ground.

Remark: We could’ve used any digital pins of the Adruino to be connected to the

right signal pins of the driver (to pin 2 & 7 and to pin 15 & 10) but we have to be

careful to change the code later on.

8.2.2 Sensors Connections:

In section 7.2.2 a. we didn’t really have any external input devices that would

control our output, but now we added a front sensor that would help us avoid any

wall collisions.

The sensor that we’re using is an infrared sensor (IR) as we discussed in previous

sections. This sensor has a ground, power, and data pins. Therefore we will

connect the ground and the power sensor pins to the microcontroller power and

ground pins. Since the sensor data output is an analog output we will connect it to

one of the analog pins of our microcontroller as we see in fig24.

Fig.24. sensor pin connection

8.2.3Programming the microcontroller using Adruino software( c++ )

Programming the microcontroller in order to run the motors without any sensor inputs

decision: The example below is a program sample on how to run the robot in forward and

backward directions.

int rightPin1 = 4;

int rightPin2 = 2;

int leftPin1 = 8;

int leftPin2 = 7;

void setup()

{

pinMode(rightPin1, OUTPUT); // pinMode: is used to configure a

specified

pinMode(rightPin2, OUTPUT); //pin to behave as an input or ouput

pinMode(leftPin1, OUTPUT);

pinMode(leftPin2, OUTPUT);

// for more details about the functions visit

//http://www.arduino.cc/playground/uploads/Main/arduino_notebook_v1-

1.pdf

}

void loop()

{

// Digital write function output either HIGH or LOW.

//In other word turns on or off a specified digital pin.

// Each motor has 2 pins. The 2 pins control the direction of the motor.

//If one set high and the other low the motor would turn clockwise.

// If we reverse the motor would turn in counter clockwise.

// Therefore in order to go forward we need both motor to run

simultaneously in //clockwise direction, whereas to go backward we need

both motor to run in a counter //clockwise direction.

// go backward

digitalWrite(rightPin1, HIGH);

digitalWrite(rightPin2, LOW);

digitalWrite(leftPin1, HIGH);

digitalWrite(leftPin2, LOW);

delay(5000);

digitalWrite(rightPin1, LOW);

digitalWrite(rightPin2, LOW);

digitalWrite(leftPin1, LOW);

digitalWrite(leftPin2, LOW);

delay(5000);

//go forward

digitalWrite(rightPin1, LOW);

digitalWrite(rightPin2, HIGH);

digitalWrite(leftPin1, LOW);

digitalWrite(leftPin2, HIGH);

delay(5000);

}

a- Programming the microcontroller in order to run the motors

according to the sensor inputs:

This code will show us how we can control our motors depending

on the input values from the sensors to the microcontroller.

*/ this program will avoid the entire encountered wall. When the robots

encounter a wall it would turn left and then move forward.

For more details about the build in functions and syntax visit.

http://www.arduino.cc/playground/uploads/Main/arduino_notebook_v1-

1.pdf

*/

int rightpin1 = 4;

int rightpin2 = 2;

int leftpin1 = 8;

int leftpin2 = 7;

int sensor = 1;

int val = 0;

int LED = 13;

void setup()

{

Serial.begin(9600); //serial. begin opens serial port and sets the

pinMode(rightpin1, OUTPUT); //baud for serial data transmission.

pinMode(rightpin2, OUTPUT);

pinMode(leftpin1, OUTPUT);

pinMode(leftpin2, OUTPUT);

pinMode(sensor, INPUT); // Here we defined the analog pin 1 (sensor

pin)

pinMode(LED, OUTPUT); // as input since we’re inputting to the

microcontroller

} // the values captured by the sensor

void loop()

{

val = analogRead(sensor); // analogRead would read a 10 bit analogue

value that

delay(1000) //ranged from 0-1023;

while ( val < 550 )

{

// As along as the value captured by sensor is less than 550, the

LED would stay //off, and the motor would go forward

digitalWrite(LED, LOW);

digitalWrite(rightpin1, HIGH);

digitalWrite(rightpin2, LOW);

digitalWrite(leftpin1, HIGH);

digitalWrite(leftpin2, LOW);

/*reading the value from the sensor inside the while loop is essential

because it would let us exit the loop if the value read is greater than 550

otherwise we will be stuck in an infinite loop. */

val = analogRead(sensor);

Serial.print("sensor_value:"); // will print the value read by sensor to

the monitor

Serial.print(val, DEC);

delay(500);

}

// when the captured value of the sensor is bigger than 550 (means

we’re //getting closer to a wall the robot will turn right, stop, and

then go back to the //top of the Loop() function.

digitalWrite(rightpin1, HIGH);

digitalWrite(rightpin2, LOW);

digitalWrite(leftpin1, LOW);

digitalWrite(leftpin2, LOW);

delay(500);

digitalWrite(rightpin1, LOW);

digitalWrite(rightpin2, LOW);

digitalWrite(leftpin1, LOW);

digitalWrite(leftpin2, LOW);

digitalWrite(LED, HIGH);

delay(1000);

}

mechatronics final design:

Fig.25. Top view

Fig.26. bottom View

Fig.27.Driver connection to microcontroller

Fig.28. Front View - infrared sensor on board

Cost:

List of parts:

S.no Product Name Vendor/

Manufacturer

Stock

Number

Price

($)

Quantity

1. Tamiya Twin Motor

Gearbox

Hobby Engineering H02055-01F 11.99 1

2. Off-Road Tire Set (2)

from Tamiya

Hobby Engineering H02033-01C 3.99 1

3. Ball Caster (Set of 2)

from Tamiya

Hobby Engineering H02016-01H 6.99 1

4. L293D Dual H-Bridge Hobby Engineering H01384-01N 3.25 4

5. Arduino Starter Pack Adafruit Industries ********* 65.00 1

6. RC battery 1