MOBILE CONTROLLED ROBOTIC ARM USING

ARDUINO AND HC-06

Eklavya Sharma

BK Birla Institute of Engineering & Technology Pilani

sharma.eklavya@hotmail.com

Abstract— In the era of technological advancement there is a

huge increase in wireless technology, and most of the work is

done using robots and robotic arm. And in this paper I have

presented the prototype of the same.

This paper deals with the design and control of RoboDroid to do

monotonous job using a smartphone only. The robot is named

‘RoboDroid’ as it utilizes concept of both Robotics and Android.

It is a mechanical arm with movable base that is controlled by an

application through Android Smartphone via Bluetooth using a

most commonly used Bluetooth module HC-06 and programmed

with Arduino Uno. The RoboDroid can function similar to the

human arm as specified by the controller or can be used for the

automation purposes. The movable base of the robotic arm is

made using two dc geared motor and two ball bearings serve the

purpose of front wheels. Robotic arm uses the servo motors

having rotational range of 0-180 degrees for its movement which

offers its précised control. To facilitate the pick and place facility

the RoboDroid is equipped with a gripper. The problem of

keeping a remote is also solved as the RoboDroid is controlled

with a smartphone application that can be installed in any

Smartphone.

The RoboDroid has many applications like material handling to

place or pick objects that are out of the reach of human, to do

hazardous work in labs, assistance in everyday life (home or

work), medical rehabilitation and many more in easier and faster

way.

Index Terms—RoboDroid, Bluetooth Module HC-06, Arduino

Uno, Automation, Robotic Arm.

I. INTRODUCTION

A robot is an automatic or virtually intelligent agent that

can carry out tasks robotically or with some supervision,

typically with the aid of a remote control. In practice, a robot is

usually an electro-mechanical machine that is guided by means

of computer and electronic programming. Robots can be

autonomous, semi-autonomous or remotely controlled [1]. The

most common manufacturing robots for commercial and

industrial use is Robotic arm. A robotic arm is a type of

mechanical arm, usually programmable, with similar functions

to a human arm; the arm may be the sum total of the

mechanism or may be part of a more complex robot [2].

Robotic arms are often used as the stepping stone to industrial

robotics and automation. RoboDroid ca be remotely controlled

or programmed to pick up or manipulate objects at a distance.

The robotic hand, can be designed to perform any desired

task such as welding, gripping, spinning etc., depending on the

application. For example, robot arms in automotive assembly

lines perform a variety of tasks such as welding and parts

rotation and placement during assembly. In some

circumstances, close emulation of the human hand is desired,

as in robots designed to conduct bomb disarmament and

disposal.

The present manuscript deals with the designing of a

robotic arm that is controlled wirelessly by Bluetooth through

an Android smartphone with Bluetooth facility known as

RoboDroid. RoboDroid is a mechanical arm with a movable

base that is controlled by Android Smartphone via Bluetooth

module using Arduino as a microcontroller platform. The

robots have to interact with their environment, which is an

important objective in the development of robots. This

interaction is commonly accomplished by means of some sort

of arm and gripping device or end effector [3].

The design process of is clearly explained in the next

section with detailed information regarding the components

used then is followed by the implementation and the results and

finally ends with conclusion.

II. DESIGN OF ROBOTIC ARM

The RoboDroid uses Arduino Uno microcontroller board

based on ATmega328 and to program this board, Arduino IDE

(Integrated Development Environment) software is used. To

provide more flexibility to the robotic arm, it is mounted over

a movable base which will carry the arm to the desired

position. Two dc geared motors are fitted in the base and two

ball bearings serve the front wheel function. For the précised

movement and control of the robotic arm five servo motors are

used having a rotational range of 0 – 180 degree, connected in

such a way that it provides 3 DOF’s (Degrees of Freedom) to

the system.. There is a gear system in gripper part that convert

the rotational motion of servo into opening and closing of the

gripper. The list components required for the designing of

RoboDroid-

A. Arduino Platform

The Arduino platform is an open source electronic

prototyping system which is meant to be used as a physical

computing platform. It is composed of two parts, the Arduino

Uno board and the Arduino IDE (Integrated Development

Environment).

1) Arduino Uno Board: The Arduino board uses the Atmel

AVR AT mega 328 microcontroller, which is the heart of the

Arduino hardware. Basically, it is designed to provide an easy

to use human changeable pin interface to the ATmega328.

There are series of Arduino boards available in the market

among them the Arduino Uno is used here. Arduino provides

more simplicity and shows compatibility with the number of

sensors and external hardware that’s why it is becoming more

and more popular among hobbyists and electronics enthusiasts

[4].

2) Arduino IDE (Integrated Development Environment):

The open-source Arduino Software also known as the Arduino

IDE (Integrated Development Environment) makes it easy to

write code and upload it to the Arduino board. It runs on

Windows, Mac OS X, and Linux. The environment is written

in Java and based on Processing and other open-source

software.

Arduino IDE is the software environment used to create the

programs, called “sketches,” that will be executed by the

Arduino hardware. It uses a modified C language compiler to

build, translate, and transmit the code to the microcontroller

board [4].

B. Bluetooth Module HC-06

The Arduino pins 0 (RX) and 1 (TX) are specified for

UART (Universal Asynchronous Receiver/Transmitter) that

control the interface with its attached serial devices. The

Bluetooth module serially communicates with the Arduino

using these two pins. However, other pins of Arduino can also

be defined as serial pins using the library “Softwareserial.h”.

This library allows to setup serial communication on (almost

any) digital pin of the Arduino Uno. The Bluetooth Module

HC-06 can be configured according to the need using the AT

commands i.e. the default name, password, baud rate etc. can

be changed as per users choice. The specifications and AT

commands of Bluetooth Module HC-06 can be easily found in

datasheet [5].

C. DC Geared Motors

For the movement of the chassis of the RoboDroid two dc

geared motors are used in rear wheels while two ball bearings

serve as the front wheel function. The operating voltage of DC

geared motor is 9-12 volt.

D. Motor Driver L293D

The L293D is quadruple high-current half-H driver. The

L293D is designed to provide bidirectional drive currents of up

to 600 milliampere at voltages from 4.5 Volts to 36 Volts.

L293D IC’s are designed to drive a wide array of inductive

loads such as relays, solenoids, DC and bipolar stepping

motors, as well as other high-current and high-voltage loads

[6]. Here, it is used to drive two DC geared motors which are

functioning as the rear wheels of the RoboDroid. The features

and specification can be found in the datasheet.

E. Servo Motors

A servomotor is a rotary actuator or linear actuator that

allows for precise control of angular or linear position, velocity

and acceleration [7]. There are five servo motors used in our

robotic arm. One for controlling the waist movement, two used

for shoulder movement, one for wrist movement and one for

the gripper control. MG995 are used here as they are tiny and

lightweight with high output power and torque. These servo

motors would provide the proper amount of power required to

maintain its own weight as well as the weight of the object

carried by the arm.

Each servo has three wires: a power wire, a ground wire,

and a Pulse-Width Modulation (PWM) wire. The PWM wire

enters one of the six PWM ports on the Arduino Uno board.

The orange colored PWM (Pulse Width Modulation) wire is

given a pulse application for a specified duration, which in turn

controls the angle of the shaft in a particular position for a

certain point of time. This modulation is famously referred to

as the PWM (Pulse Width Modulation). The servomotor

expects a coded signal every few seconds. The duration of the

pulse determines the angular degree of the shaft. The wire

configuration and specification of MG995 can be seen in the

datasheet.

F. Power Supply

There are two DC power source used here. To power up the

Arduino and motor driver a 7.2 V LiPo (Lithium Polymer)

Battery is used with 900 milliampere hour current rating. And

to power up the servo motors 7.2 Volt LiPo (Lithium Polymer)

Battery with high current rating (3000 milliampere hour) is

used.

III. ASSEMBLING THE ROBODROID

A. Making The Chassis

The chassis carry the whole weight of the robot and

functions as the moving base of the RoboDroid. The base will

carry the robotic arm to the desired position. The base is made

up of sun mica sheet. The Arduino board, motor driver

circuitry and the power supply is bolted on the movable base.

For the rear wheel’s function DC geared motors are used and

ball bearings are functioning as front wheel as shown in Fig. 1

shown below.

Fig. 1. Chassis of RoboDroid

B. Mounting Robotic Arm

The base (waist) of the robotic arm is bolted on the chassis.

The waist offers précised position control of 0 to 360 degrees.

The waist servo motor control the waist movement, two motors

control shoulder movement, one servo motor control wrist

movement and the remaining one control the gripper

movement. There is a gear system in gripper part that convert

the rotational motion of servo into opening and closing of the

gripper.

Fig. 2. Complete assembly of RoboDroid

SNO. Specifications Values

1. Weight 1.5 kg

2. Height 40 cm

3. Length 33.3 cm

4. Width 16.2 cm

5. Wheel Diameter 7 cm

TABLE I. GENERAL SPECIFICATIONS OF THE ROBODROID

IV. HARDWARE CONNECTIONS WITH ARDUINO BOARD

A. Arduino And Bluetooth Module

The Arduino pins 0 and 1 are specified for Universal Asynchronous

Receiver/Transmitter (UART) that control the interface with its attached serial

devices. These pins of Arduino are connected with the RXD and

TXD pins of Bluetooth module HC-06. The Vcc and GND

(ground pin) of HC-06 is powered with the 3.3 Volt supply pin

and ground pin of Arduino. Figure 3 shows the connection

between Arduino Uno board and Bluetooth module HC-06.

The circuit schematic is made using the open source software

Fritzing.

Fig. 3. Connection between Arduino and Bluetooth module HC-06

B. Arduino And Motor Driver IC L293d

To drive the geared dc motors which are fixed on the base

of RoboDroid motor driver IC L293D is used. The power

supply to Arduino board and motor driver L293D is given by a

7.2 Volts LiPo (Lithium Polymer) battery. Figure 4 shows the

connection between the motor driver IC, Arduino board and

DC motors.

Fig. 4. Connecting L293D with DC motors and Arduino

C. Arduino and Servo Motors

The servo motors of the RoboDroid are needed to be

connected to the specific pins of Arduino Uno board. Five

servo motors are used in the RoboDroid, one for the waist, two

for the shoulder movement, one for wrist and one for the

gripper movement. Only the waist servo motor has the

rotational angle of 0-360 degrees while others have the

rotational motion of 0-180 degrees.

An isolated high current power supply is required for the

servo motors. The orange colored PWM (Pulse-Width

Modulation) wire of the servo motors goes to the Arduino Uno

board. The red colored power wires of all the servo motors are

shorted and connected with the positive terminal of the 7.2

Volts LiPo (Lithium Polymer). Similarly, the ground pin of

Arduino Uno board, the black colored ground wire of all five

servo motors is connected with negative terminal of the battery.

Figure 5 shows the schematic connection between the Arduino

Uno board and the servo motors.

Fig. 5. Schematic connection between Arduino Uno and servo motors

V. ROBODROID WORKING FLOWCHART

The RoboDroid functions starts with the human input from

an Android smartphone using a mobile application. The mobile

application setups a Bluetooth connection between the Arduino

Board and the smartphone for communication via the

Bluetooth module HC-06. The instructions coming from the

mobile is received by the Arduino board due to the serial

communication between the Arduino and Bluetooth module

and the microcontroller processes the data and gives command

to the end effectors and the RoboDroid gives the mechanical

output.

Fig. 6. Working flow chart of robotic arm

VI. ARDUINO PROGRAMMING

There are two major tasks in programming the Arduino

board to control the RoboDroid using the mobile application.

First, to set up the serial connection between the Arduino Uno,

Bluetooth module HC-06 and the smartphone and reading the

data send from the Mobile application via Bluetooth. Second,

processing the data read and giving signals to the servomotors

and the DC geared motors.

A. Serial Communication

To begin the serial communication, the statement

“Serial.begin(speed)” is used that communicate over the pins 0

and 1 of the Arduino board. It opens the serial port and sets the

data rate in bits per second (baud) for serial data transmission.

Now to get the number of bytes (characters) available for

reading from the serial port “Serial.available( )”is used. The

incoming serial data sent from the mobile application is read

using the function “Serial.read( )”.

B. Interfacing DC Motor

To interface DC motor with Arduino Board L293D IC is

used. The input pins of the IC are connected with Arduino and

the output pins of the L293D IC is connected with the DC

motors. The “pinmode(pin, mode)” function configures the

specified pin to behave either as an input or an output. The

mode for the DC motors is ‘OUTPUT’and the pin number is

up to the user’s choice. After setting the pinmode the

“digital.write(pin, value)” writes the high or low value to the

specified digital pin and according to the human input through

mobile it can enable or disable the DC geared motors. The

speed of the motor can be varied using analog.write(pin, value)

function in Arduino IDE (Integrated Development

Environment).

C. Interfacing Servo Motor

Servo motor is interfaced using the library “Servo.h”. This

library allows an Arduino board to control servo motors.

Servos have integrated gears and a shaft that can be precisely

controlled. Standard servos allow the shaft to be positioned at

various angles, usually between 0 and 180 degrees. The

“servo.attach(pin)” function attaches the Servo variable to a

pin. After attaching the servos with the specified pin of

Arduino board the “servo.write(angle)” function is used to

write values to the servo and controlling the shaft accordingly .

In our context the angle values to the servo is provided by the

human using the mobile application.

VII. ANDROID APPLICATION DEVELOPMENT

MIT App Inventor

MIT App Inventor is an open-source web application that

allows the users to make software applications for Android

operating system. Even with limited programming experience

one can easily create an Android Application. App Inventor for

Android is a visual language that relies on simple programming

blocks that users can drag and drop to create software

applications. It was made by Google and it is maintained by the

Massachusetts Institute of Technology (MIT). And MIT App

Inventor 2 is the latest version of App Inventor.

MIT app inventor doesn’t support Internet Explorer

browser. To use MIT App Inventor 2 for Android, to develop

mobile application you must use a compatible browser.

Currently the supported browsers are:

Google Chrome 29+

Safari 5+

Firefox 23+

The RoboDroid application developed using MIT App

Inventor 2 is shown in Fig. 7.

Fig. 7. Mobile Application To Control RoboDroid

RoboDroid application is able to control the movement of

the base of the robotic arm as well as the robotic arm itself. The

application is divided into two parts one is Car control and

other one is Arm Control. For the successful operation of the

application, first of all press the Bluetooth button which will

switch on the Bluetooth if it is not enabled already. After the

Bluetooth is enable the same Bluetooth button will show the

list of nearby available Bluetooth devices. From the list of

Bluetooth devices choose the Bluetooth module HC-o6. To

connect the smartphone with Bluetooth module HC-06

password is needed. The default password for HC-06 module is

1234. Using the AT (Attention) commands the default

password can be changed. After setting the Bluetooth

connection RoboDroid can be easily controlled.

Car control part moves the base of the RoboDroid i.e. the

DC geared motors. For moving the base in a particular

direction the arrow key showing that direction is pressed and

the base will move until the key is released.

Arm Control part of the mobile application controls the arm

of the RoboDroid i.e. the servo motors. When any servo

control key is pressed the servo motor associated with that key

moves by 10 degree. The up arrow increases the servo angle by

10 degrees and down arrow decreases the servo angle by 10

degrees. The Start button performs a specific task without the

human intervention. The start button can be assigned to

perform any task by suitably programming the Arduino board.

VIII. APPLICATIONS

This RoboDroid can be put to use in various types of

applications as follows:

The RoboDroid can perform robotic functions from

outside the hazardous chambers looking through a

glass door

For controlling the RoboDroid there is no need of

keeping any remote as it can be controlled through

mobile application which can be installed in any phone

Prototype for a Bomb disposal robot

Advanced robotic toys, controlled through mobile

application

Automatic metal cutting machines and in industrial

manufacturing in particular desire profiles, which are

located in high temperature zones.

IX. FUTURE IMPLEMENTATION

RoboDroid is so far designed to lift the medium sized

object. With advanced tools and high capacity equipment

RoboDroid can perform heavier tasks. Furthermore, the user

interface of the mobile application can be improved. The

RoboDroid can be interfaced with the Neurosky or any other

mind interfacing device and can be controlled through mind

thoughts.

X. CONCLUSION

This paper has undergone with the basic design and control

of RoboDroid using a mobile application. The steps to make a

mobile controlled robotic arm are observed and explained

clearly. The paper dealt with serial communication between

mobile and Bluetooth module HC-06, interfacing DC motors

and interfacing servo motors. The objective of this paper to

design a prototype of mobile application controlled robotic arm

which can be employed to automation and commercial use.

The RoboDroid is designed very efficiently and it is

capable to lift the objects of medium weight accurately and

precisely.

ACKNOWLEDGMENT

I would like to express my sincere gratitude to my guide

Prof. (Dr.) Rardchawadee Silapunt (Depsrtment of Electronics

Engineering) of King Mongkut’s University of Technology

Thonburi, Bangkok (Thailand) for her excellent direction and

encouragement. I am also thankful to Prof. Satish Rai

(Assistant Professor) BKBIET Pilani, for his suggestion and

support. I express much gratitude to my family, friends and

everyone who contributed to this project.

REFERENCES

[1] Jegede Olawale, Awodele Oludele, Ajayi Ayodele,

“Development of a Microcontroller Based Robotic Arm”, in

Proceedings of the 2007 Computer Science and IT Education Conference pg: 549-557.

[2] https://en.wikipedia.org/wiki/Robotic_arm

[3] A.Rama Krishna, G. Sowmya Bala, A.S.C.S. Sastry, B. Bhanu

Prakash Sarma, Gokul Sai Alla, "Design And Implementation of

A Robotic Arm Based On Haptic Technology" ISSN: 2248-

9622, www.ijera.com Vol. 2, Issue 3, May-Jun 2012, pp.3098-

3103

[4] http://www.codevista.net/269/introduction-to-the-arduino-platform-and-why-you-need-one

[5] http://www.codevista.net/182/how-to-connect-bluetooth-module-hc-06-with-arduino-uno

[6] http://www.ti.com/lit/ds/symlink/l293.pdf

[7] https://en.wikipedia.org/wiki/Servomotor

[8] http://www.codevista.net/154/how-to-make-a-mobile-controlled-robotic-arm-using-arduino-uno

[9] ai2.appinventor.mit.edu

[10] http://www.arduino.cc