DESIGN
OF ANDROID CONTROLLED ROBOT
3.1
Experimental setup
The block diagram
of beagle bone based live streaming android controlled robot is shown in Fig.
2. 1.
·
Android Phone:
The designated web page for controlling the robot movement is accessed using
the android smartphone. Using the smartphone, robot control signal is
transmitted over the Wi-Fi to the processor. The live video signal transmitted
form the cameracan be displayed on smartphone.
·
Wi-Fi Router: The
router provides the RF signal transmission channel for control signal transmission
from controller device i.e. from android smart phone to the processor and also
transmits the live video signals to the video display module.
·
Beagle Bone: The
Beagle Bone Board has ARM Cortex A8 processor. The video signals from the web
cam is processed and sent by beagle bone. The received control signals from the
android phone, is processed and this processed information is sent to the motor
controlling relay circuit.
·
Relay Circuit: This
circuit receives the motor control information from the beagle bone and it
controls the motor rotation accordingly.
·
Web Cam: the
camera will capture the image, convert it to RAW data steam, and send it to the
Beagle Bone.
·
Motor:The
proposed system uses two motors. These motors will rotate in clockwise and
anti-clockwise direction according to the switching action of the relay.
3.2
Working Mechanism:
The
12V DC battery is used as power source in this project. This 12 V DC supply is
regulated down to 5V using LM7805 and given to the BeagleBone and also
regulated down to 9V using LM7809 and given to Wireless Router. The 12V battery
is directly connected to two 12V DC motors.
In
this project android smartphone act as a robot controller . The android device will connect to the
processor mounted on the robot by using its IP (Internet Protocol) address. The
BeagleBone is connected to Wi-Fi router through Ethernet cable. The Wi-Fi
Router will assign one IP address from the pool of IP addresses to the
BeagleBone after receiving the IP address of BeagleBone. After connecting to
the BeagleBone, the designated web page is accessed on the android device. In
the accessed web page, there will be motor controlling icons and video
streaming icon.
Whenever any motor directional icons
pressed on the web page, the control signals will be transferred to BeagleBone
through Wi-Fi. The BeagleBone sets the values on the general purpose outgoing
signal pins according to control signals received. Pin 3, pin 3, pin 30, pin 45
are the general purpose input/output pins that are used to control the robot.
The control signals from the BeagleBone is in the form of binary sequence are
sent to the relay circuit serially. The
relay circuits will switches to either 0V or 12V based on the control signal.
The DC motor will rotates in clockwise and anticlockwise direction.
When
the camera icon is pressed, the camera will starts capturing the video signals
of the surrounding environment and covert it to the raw frame data. This data
is sent to the BeagleBone serially through USB port. The Mjpg-streamer is
software in the BeagleBone that takes raw frame data from the webcam and
outputs a stream in the MJPG format, a series of JPEG images. The webcam stream
is forwarded to the Mjpg streamer server to process. Then the stream is
converted to video format. This real time video is sent over Wi-Fi and displayed
on the user display module.
3.3 Data flow and processing of program
In this project,
following operations have been followed for the control of robot and real time
video streaming.
·
As the android phone notice the presence
of Wi-Fi network, the phone will authenticate to the network and obtain network
information.
·
The android application in the mobile
initialized. With the specified IP address, the BeagleBone can be accessed. The
designated web page is accessed by using the name of the particular web page.
·
The control panel for motor control and
live streaming is visible on the android phone.
·
When any icon on the smartphone screen
is pressed, the signal is transferred to the BeagleBone through Wi-Fi. The
BeagleBone process the signal and generates the digital bit patters for the
robot movements. This control signals are sent to relay circuits that drives
the motor.
The
flowchart for the process flow is given in the figure 3. 2.
3.4.1
BeagleBone
The BeagleBone Black
a low cost ARM Cortex-A8 based processor size as small as a credit card. It has
been equipped with a minimum set of features to allow the user to experience the
power of the processor and is not intended as a full development platform as
many of the features and interfaces supplied by the processor are not
accessible from the BeagleBone Black via onboard support of some interfaces. It
is not a complete product designed to do any particular function. It is a
foundation for experimentation and learning how to program the processor and to
access the peripherals by the creation of your own software and hardware. It
also offers access to many of the interfaces and allows for the use of add-on
boards called capes, to add many different combinations of features.
Key
components
·
SitaraAM3359AZCZ100
is the processor for the board.
·
Micron
512MBDDR3L is the Dual Data Rate RAM memory.
·
SMSC Ethernet
PHY is the physical interface to the network.
·
Micron eMMC is
an onboard MMC chip that holds up to 2GB of data.
·
HDMI Framer
provides control for an HDMI or DVI-D display with an adapter.
The parts of the Beagle Bone that is
used are:
Power
supply: The board can be
powered from four different sources:
·
A USB port on a
PC
·
A 5VDC 1A power
supply plugged into the DC connector.
·
A power supply
with a USB connector.
·
Expansion
connectors
Like other electronic
component, the supply pin is the most important. The ideal voltage for Beagle
Bone Black is 5V (Direct Current). It should not be higher than 5.2V because it
will blow up the circuit. It should also not be less than 4.7V because it will
not help in circuit operation. We are using DC connector to power up the BeagleBone.We
have various type of supply such as battery, DC adapter, AC power supply with
step down transformer and bridge rectifier. We are making use of DC battery
supply which is then stepped down to 5V to the Beagle Bone using LM7805
regulator.
GPIO
Pins:
There are 92 General Purpose Input/output
(GPIO) pins are available in the BeagleBone (Appendix A). Since the Linux is
file based system, every GPIO pins have its own file system. Any instruction to
the particular pin will generate the appropriate output signal individually.Pin
numbers 2, 3, 30, 45 are used for our project purpose. These pins will generate
digital bits that will control the motor rotation.
3.4.2
Relay Circuits to drive DC Motors
There are 2 two-way DC motor
controller relay circuits used in the project, which operates the motors in two
directions. The sequence of excitation of two rotor coils (A and B) is as shown
in the table 3.1.These inputs are given to the relays circuits, which drives
the corresponding DC motors.
Table 3.1: Excitation
sequence of coils in the two DC motors
A
|
B
|
Motor Status
|
0
|
0
|
off
|
0
|
1
|
clockwise
|
1
|
0
|
Counter-clockwise
|
1
|
1
|
off
|
3.4.3
D. C Motor
A DC motor relies on the fact that like magnet poles repels and
unlike magnetic poles attracts each other. A coil of wire with a current
running through it generates an electromagnetic field
aligned with the center of the coil. By switching the current on or off in a coil
its magnet field can be switched on or off or by switching the direction of the
current in the coil the direction of the generated magnetic field can be
switched 180°.
A
simple DC motor typically
has a stationary set of magnets in the stator and an armature with
a series of two or more windings of wire wrapped in insulated stack slots
around iron pole pieces (called stack teeth) with the ends of the wires
terminating on a commutator. The armature includes the mounting bearings that
keep it in the center of the motor and the power shaft of the motor and the
commutator connections. The winding in the armature continues to loop all the
way around the armature and uses either single or parallel conductors (wires),
and can circle several times around the stack teeth as shown in the Fig.3.4.2.
The total amount of current sent to the coil, the coil's size and what it's
wrapped around dictate the strength of the electromagnetic field created. The
sequence of turning a particular coil on or off dictates what direction the
effective electromagnetic fields are pointed. By turning on and off coils in
sequence a rotating magnetic field can be created. These rotating magnetic
fields interact with the magnetic fields of the magnets (permanent or electromagnets) in the
stationary part of the motor (stator) to create a force on the armature which
causes it to rotate. The commutator allows each armature coil to be activated
in turn. The current in the coil is typically supplied via two brushes that
make moving contact with commutator.
Fig.
3. 4. Construction diagram of DC motor
This project uses two
bipolar 12V DC motors. One is for the left wheel and the other one for the
right wheel. The outputs of relay are given as input to its corresponding DC
motors activates one of the coil and the stepper motor rotates accordingly.he
DC motor has the following features and parameters:
·
Operating
Range: 6-12 VDC
·
The load
current:120 mA.
·
Speed: 45 RPM
·
DC
reversible motors
·
Solder type
terminal
·
High torque
construction
·
Insulation
resistance: 20 M Ohm
·
Dielectric
Strength: 250VDC
3.4.4
Camera
3.4.5
Wireless Router
3.4.6
Voltage regulators
3.5 Advantages
·
Robots can be
controlled remotely
·
Real time video
signal helps to monitor the surrounding environment.
3.6Applications
·
Scientific
Remote control vehicles have various
scientific uses including working in hazardous environments, the Deep Ocean,
and exploration.
·
Military
and law Enforcement
Remote controlled vehicles are used
by many military for enemy tracking, bomb-squads to defuse or detonate
explosives.
·
Search
and Rescue
It can be used to save lives of
both people along with solders in case of terrorist attacks, natural calamities
and disaster.
·
Recreation
and Hobby
Toys and cars used for
entertainment purpose. These include on-road cars, off-roads trucks, boats,
airplanes and helicopters.
No comments:
Post a Comment