Design and Implementation of a WiFi Based Home Automation System

Abstract

This paper presents a design and prototype implementation of new home automation system that uses WiFi technology as a network infrastructure connecting its parts. The proposed system consists of two main components; the first part is the server (web server), which presents system core that manages, controls, and monitors users' home. Users and system administrator can locally (LAN) or remotely (internet) manage and control system code. Second part is hardware interface module, which provides appropriate interface to sensors and actuator of home automation system. Unlike most of available home automation system in the market the proposed system is scalable that one server can manage many hardware interface modules as long as it exists on WiFi network coverage. System supports a wide range of home automation devices like power management components, and security components. The proposed system is better from the scalability and flexibility point of view than the commercially available home automation systems.

Full text

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Abstract—This paper presents a design and prototype
implementation of new home automation system that uses WiFi
technology as a network infrastructure connecting its parts. The
proposed system consists of two main components; the first part is
the server (web server), which presents system core that manages,
controls, and monitors users’ home. Users and system administrator
can locally (LAN) or remotely (internet) manage and control system
code. Second part is hardware interface module, which provides
appropriate interface to sensors and actuator of home automation
system. Unlike most of available home automation system in the
market the proposed system is scalable that one server can manage
many hardware interface modules as long as it exists on WiFi
network coverage. System supports a wide range of home
automation devices like power management components, and
security components. The proposed system is better from the
scalability and flexibility point of view than the commercially
available home automation systems.
Keywords—Home automation, Wireless LAN, WiFi,
MicroControllers
I. INTRODUCTION
A. Overview [1]
OWADAYS home and building automation systems are
used more and more. On the one hand, they provide
increased comfort especially when employed in a private
home. On the other hand, automation systems installed in
commercial buildings do not only increase comfort, but also
allow centralized control of heating, ventilation, air condition
and lighting. Hence, they contribute to an overall cost
reduction and also to energy saving which is certainly a main
issue today.
Existing, well-established systems are based on wired
communication. Examples include BACnet, LonWorks and
KNX [1]. Employing a traditional wired automation system
does not pose a problem as long as the system is planned
before and installed during the physical construction of the
building. If, however, already existing buildings should be
augmented with automation systems, this requires much effort
and mush cost since cabling is necessary.
Obviously, wireless systems [1] can come to help here. In
the past few years, wireless technologies reached their
breakthrough. Wireless based systems, used every day and
everywhere, range from wireless home networks and mobile
phones to garage door openers. As of today, little comparative
research of wireless automation standards has been done,
although such knowledge would provide valuable information
to everyone looking for the most suitable system for given
requirements.
Ahmed ElShafee, Ph.D., Assistant Professor, Faculty of Computer Science
and IT, Ahram Canadian University, 6th October City, Giza, Egypt. & Member
IEEE, aelshafee@ieee.org
Karim Alaa Hamed, B.Sc., Teaching assistant, Faculty of Computer
Science and IT ,Ahram Canadian University, 6th October City, Giza, Egypt.,
karimalaahamed@hotmail.com
B. Features and benefits of home automation systems [2]
In recent years, wireless systems like WLAN have become
more and more common in home networking. Also in home
and building automation systems, the use of wireless
technologies gives several advantages that could not be
achieved using a wired network only.
1) Reduced installation costs: First and foremost, installation
costs are significantly reduced since no cabling is
necessary. Wired solutions require cabling, where
material as well as the professional laying of cables (e.g.
into walls) is expensive.
2) Easy deployment, installation, and coverage: Wireless
nodes can be mounted almost anywhere. In adjacent or
remote places, where cabling may not be feasible at all,
e.g., a garden house or the patio, connection to the home
network is accomplished instantly by simply mounting
nodes in the area. Hence, wireless technology also helps
to enlarge the covered area.
3) System scalability and easy extension: Deploying a
wireless network is especially advantageous when, due to
new or changed requirements, extension of the network is
necessary. In contrast to wired installations, additional
nodes do not require additional cabling which makes
extension rather trivial. This makes wireless installations
a seminal investment.
4) Aesthetical benefits: As mentioned before, placement of
wireless nodes is easy. Apart from covering a larger area,
this attribute helps to full aesthetical requirements as well.
Examples include representative buildings with all-glass
architecture and historical buildings where design or
conservatory reasons do not allow laying of cables.
5) Integration of mobile devices: With wireless networks,
associating mobile devices such as PDAs and
Smartphones with the automation system becomes
possible everywhere and at any time, as a device's exact
physical location is no longer crucial for a connection (as
long as the device is in reach of the network).
Typical examples include an engineer who connects to the
network, performs a particular management task, and
disconnects after having finished the task; or control of blinds
using a remote control.
For all these reasons, wireless technology is not only an
attractive choice in renovation and refurbishment, but also for
new installations.
II. SYSTEM ANALYSIS
A. Problem definition
Home automation systems face four main challenges [3],
these are high cost of ownership, inflexibility, poor
manageability, and difficulty achieving security. The main
objectives of that research is to design and to implement a
cheap and open source home automation system that is
capable of controlling and automating most of the house
appliance through an easy manageable web interface to run
Design and Implementation of a WiFi Based
Home Automation System
Ahmed ElShafee, Karim Alaa Hamed
N
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and maintain the home automation system. The proposed
system has a great flexibility by using WiFi technology to
interconnect its distributed modules to home automation
server. That will decrease deployment cost and will increase
the ability of upgrading, and system reconfiguration.
System will make use of secure wireless LAN connections
between distributed hardware modules and server, and secure
communication protocols between users and server.
B. Proposed system feature
The proposed system is a distributed home automation
system, consists of server, hardware interface modules. Server
controls hardware one interface module, and can be easily
configured to handle more hardware interface module. The
hardware interface module in turn controls its alarms and
actuators. Server is a normal PC, with built in WiFi card, acts
as web server. The webserver software is developed using
asp.net technology, so web server should support asp
application and.net frame work 4.0, like IIS7.0 for windows
OS.
System can be accessed from the web browser of any local
PC in the same LAN using server IP, or remotely from any PC
or mobile handheld device connected to the internet with
appropriate web browser supports asp.net technology through
server real IP (internet IP).
WiFi technology is selected to be the network infrastructure
that connects server and hardware interface modules. WiFi is
chosen to improve system security (by using secure WiFi
connection), and to increase system mobility and scalability.
Even if, user intends to add new hardware interface modules
out of the coverage of central access point, repeaters or
managed wireless LAN will perfectly solve that problem.
The main functions of the server is to manage, control, and
monitor distrusted system components, that enables hardware
interface modules to execute their assigned tasks (through
actuators), and to report server with triggered events (from
sensors).
In setup mode, user can add and remove hardware interface
modules, and can create basic macros involving simple
triggers and to customize the macros to perform complex
series of events. Macros can be activated manually or as a
reaction for certain trigger like motion sensors and
surveillance cameras. User can also program macros to
activate at random; this feature allows your system to turn the
lights on and off at random or semi-random intervals.
In running mode, if hardware interface modules report
server with received events and execute their pre-programmed
macros.
Hardware interface modules are directly connected to
sensors and actuator through direct wires connections.
Hardware interface modules has the capabilities to control
energy management systems like lighting, thermostats and
HVAC (heating, ventilation, and cooling) systems, and
security systems (door locks, cameras, motion detectors, fire
alarms…).
C.System requirements
The following list gives an overview of the most important
requirements of the proposed system
1) User friendly interface: User can easily manage system
locally or remotely home automation system, through
easy web based interface.
2) Security and authentication: Only authorized user can
login to the system (locally, or remotely) in order to
manage, control, & monitor. If system detects intruders it
should immediately alert the system owner and lock login
capability for a while.
3) Low cost per node / High node count: Thinking of
building automation, hundreds of nodes may be needed to
provide automation. However, the market requires
competitive performance (compared to wired networks)
to be delivered at this low system cost. Additionally, also
protocols need to scale to high node count e.g., ensuring
message delivery
4) Large area coverage: Another challenge lies in the fact
that devices of a building automation system are
dispersed over large areas. Since transceivers must not
consume so much power, they cannot be built with a
transmission range sufficient for sensors to reach
associated controllers or actuators directly. Also, they
may rely on an infrastructure of access points and a wired
backbone network (or particularly sensitive receivers).
5) System Scalability: Scalability is the ability of a system,
network, or process, to handle growing amount of work
in a capable manner or its ability to be enlarged to
accommodate that growth. For example, system
upgrade/downgrade by adding/removing hardware
interface module should be easy and systematic task.
III. SYSTEM DESIGN AND IMPLEMENTATION
A. Proposed Home Automation System layout
As mentioned the proposed home automation system
consists of three main modules, the server, the hardware
interface module, and the software package. The following
figure (1), shows the proposed system layout.
Secure WiFi technology is used by server, and hardware
interface module to communicate with each other. User may
use the same technology to login to the server web based
application. if server is connected to the internet, so remote
users can access server web based application through the
internet using compatible web browser.
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Fig. 1 The proposed home automation system layout
B. Proposed Home Automation System Functions (Home
Area Interface)
The proposed home automation system has the capabilities
to control the following components in users home and
monitor the following alarms;
xTemperature and humidity
xMotion detection
xFire and smoke detection
xDoor status
xLight level
xVideo monitoring
The proposed home automation system can control the
following appliance;
xSerine
xLights on/off/dim
xHVAC on/off
xDoor lock
xWindow shutdown
xOn/off different appliance
C.User Classes and Characteristics
The proposed home automation system is designed as a tool
for the casual user. A casual user; shall be defined as one
possessing general knowledge of the Microsoft Windows
operating system and general knowledge of using the Internet
by employing a standard browser such as Microsoft Internet
Explorer General user; who will have the most use of the
system functionality. Administrator; who will control the
access and permissions policy of the system, and can add and
delete user accounts, anything that a general user can perform,
the administrator can also perform.
D.Design and Implementation Constraints
The Proposed home automation system is implemented
using ASP, HTML and CSS. The server application is
implemented in ASP.Net, and the embedded hardware
interface application shall be implemented using C Processing
Language.
E. Assumptions and Dependencies
xThe component of the system will always be connected
xEach User must have a User ID and password
xThere is only one Administrator.
xServer must always run under windows system
xThere should be Internet connection available.
xProper browsers should be installed
xProper Hardware Components are available
xUser is capable of using a computer
F. Software design concept
Software of the proposed home automation system is
divided to server application software, and Microcontroller
(Arduino) firmware.
The server application software package for the proposed
home automation system, is a web based application built
using asp.net, Microsoft Visual Studio 2010. Server
application software runs on windows OS, requires IIS web
server, and “.Net” version 4.0 being installed. The server
application software can be accessed from internal network or
from internet if the server has real IP on the internet using any
internet navigator supports asp.net technology. Server
application software is responsible of setup, configuration,
maintain the whole home automation system. Server use
database to keep log of home automation system components,
we choose to use XML files to save system log.
The Arduino software, built using C language, using IDE
comes with the microcontroller itself. Arduino software is
responsible for collecting events from connected sensors, then
apply action to actuators and pre-programed in the server.
Another job is to report the and record the history in the server
DB.
Figure(2) shows the architecture of the proposed home
automation system. The following figure (3) shows classes
diagram of proposed system, which consists of five main
classes.
G.Classes description
1) dataSourceLog:
Create a log text file in a specific path. This log file has a
new log entry, ready to be filled with data. A log entry has the
date of the day and a log number.
Ɣ writeToLogEntry: Function to write the data into the log
file; using a stream writer to convert it and save it into a
TEXT file.
Ɣ readLog: Read from the file line by line, the log entry
with the data
Ɣ readNewLog: This function reads the new log entry as
just been saved.
2) datasourceXML:
Ɣ responsible for all operations regarding the main XML
files, User, Sensors and Automation
Ɣ addUser: Function of adding a new user to the system
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Fig. 2 Proposed home automation system architecture
Fig. 3 proposed system class diagram
Ɣ getUserHex: User Hex is a security issue. Checking
progress will not only be on the username and password, but
also on a random generated number for each user. This
number changes every time the user logs into the system
Ɣ checkUser: Check if the entered username and password
is the exact match with the saved XML file or not
Ɣ getSensorStatus: Get a sensor last status from the file
Ɣ automationTime: Sets the time that the automation is
supposed to be activated, in hours, minutes, and seconds.
The following are of the same functionality; which is to
change the data of a specific attribute in the XML file given
from the function name: automationMotion, automationDoor,
automationTemp, automationAppliance, automationDuration,
automationSecurity
3) Automator:
Responsible for all automation processes, including the
monitoring of the environment for conditions that matches the
automation rules configured by the user
Ɣ statusInitializer: set all the sensors and actuators back to
its initial values. Sensors will be set to 0, and the actuators
will be set to the last update in the XML data files.
Ɣ getDataFromXML: Get data from XML function
Process: check every one of the sensors and appliance
either it contains the key word from the XML file dictionary
or not. If it contains the key word it sends the data to check
dependency function.
Ɣ checkDependency: check if the automation of a specific
sensor in an automation is dependent on any other sensor,
appliance, or a specific time to be activated.
Ɣ watcher: Watcher function acts like a guard; it keeps
watching the timer and all other sensors and actuators last
updated statuses from the XML file. When all conditions of an
automation becomes true. Automation executed.
Ɣ processSensor: checks sensors to see the last updates, in
case of any dependent automation on one of the sensors.
Ɣ activateAppliance: Activates any appliance that should be
activated according to the running automation.
4) Manager:
Responsible for maintaining the whole system in general
and initializing all that is needed for further operation when
the system is first started
Ɣ Processor: initializes and load all needed data into the
system and establish communication with the hardware
module
Ɣ addAutomatorObject: load an automation entry into the
system to be watched
Ɣ deleteAutomation: deletes an automation from the system
and XML file and also stops the system from watching it
anymore
Ɣ getNewAutomation: get all the automation that are
assigned to run today
Ɣ goManual and goAutomation: toggle the system from
manual control to automatic control, needed if the user wishes
to stop any automation and have full control
Ɣ addAutomatorObject: load an automation entry into the
system to be watched
Ɣ deleteAutomation: deletes an automation from the system
and XML file and also stops the system from watching it
anymore
Ɣ getNewAutomation: get all the automation that are
assigned to run today
Ɣ goManual and goAutomation: toggle the system from
manual control to automatic control, needed if the user wishes
to stop any automation and have full control.
5) connectionWifi:
Responsible for all communication to the hardware module
and the data transmission in between
Ɣ wifiIntializer: initialize the connection to a specified
socket
Ɣ writeToSocket: sends data to the specified socket in the
form of a string
Ɣ readFromSocket: read data from socket after sending it a
variable to flag the type of data that is needed to be received
The following are of the same functionality, which is to get
the latest status of the specified sensor given in the function
name: getDoor, getMotion, getTemperature
The following are of the same functionality, which is to
toggle the specified appliance given in the function name to a
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new state: switchLights, switchAC, switchAlarm
H.Data Flow
Ɣ Login interface Æ Security Module Æ Data Source Æ
Logger Æ Log Interface
To start using the system; the user has to use the login
interface to log in into the system. Data passes a security
module to be transferred to a 128-bit hex key and checked for
availability in the data source represented in XML files. Then
the system writes this action into the logger which in turn
sends it to the Log interface.
Ɣ Status Interface Æ Communication Module Æ Hardware
Interface Æ Logger Æ Log Interface.
Acquiring the status of an actuator or a sensor using the
Status interface, is done by receiving these data directly from
the communication module, which in turn gets the data
required through the Hardware interface represented into the
microcontroller. While this process is done and the status is
checked repeatedly, any changes will be written in the Logger
and appears in the Log interface.
Ɣ Control Interface Æ Communication Module Æ
Hardware Interface Æ Logger Æ Log Interface.
Changing the status of an actuator through the Control
interface, is done by sending data directly to the
Communication Module, which in turn sends it to Hardware
interface represented in the microcontroller to apply the
required changes. During the process of sending data and
changing the actuator, changes are being written into the
Logger and appear in the Log interface.
Ɣ Control Interface Æ Data Source.
After changing a status of an actuator and writing it into
the log using the Control interface, these changes are being
written in the Data Source represented in XML files for later
checks.
Ɣ Automator Æ Data Source.
Setting up a new Automation for the system to do is done
by the Automation interface, which just saves it into the Data
Source XML files; waiting to be activated.
Ɣ Status, Control, Data Source Æ Automator Æ
Communication Module Æ Hardware Interface Æ Logger Æ
Log Interface.
The Automator is responsible for executing the automations
that have been already saved by the users. In order to do that,
it gathers data from the Data Source XML files, Status, and
Control interfaces; compares these data with the entered ones
in the XML files. Then it sends the appropriate changes
required to the Communication Module in order to apply it in
the Hardware Interface. During this process changes are being
written in the Logger and appear in the Log Interface.
I. Hardware design
The second part of the proposed home automation system
design was the choosing of a suitable micro-controller. The
requirements for the micro-controller are; a RS232 port, a fair
amount of output Digital I/O, and a reasonable speed.
Fig. 4 Proposed system use cases
Also a reasonable amount of EEPROM was needed to
enables the system to store device status, and username and
passwords related to login, so that data is not lost in the case
of power outages.
Arduino is a readymade and open source evaluation Kit
based on a 8-bit Atmel microcontroller. Arduino
Microcontroller is the core of hardware interface module,
which is responsible for exchanging data between home
automation server from one side (through WiFi module), and
sensors, and actuators from the other side. Arduino
communicate with WiFly module through RS232 protocol. If
sensors and actuators are directly connected to hardware
interface module, an isolating interface is needed to protect
Arduino from interference caused by home automation
components.
Figure (5) shows the WiFly arduino shield PCB layout,
Figure (6) shows the arduino shield PCB layout of a three
input alarms. Figure (7) shows the arduino shield PCB layout
of a three output actuators.
J. Hardware layout
Hardware consists of four different PCBs, the Arduino PCB
(ready-made), WiFi shield PCB, 3 input alarms PCB, and 3
output actuators PCB.
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Fig. 5. WiFi Shield PCB layout
Fig. 6 Three input alarms PCB layout
Fig. 7 Three output actuators PCB layout
IV. IMPLEMENTED PROTOTYPE SNAP SHOOTS
Figures (8) and (9) show snaps shots from proposed system
user interface. For more information regarding the
functionality and features of the proposed Home Automation
System, check the prototype published on line in the following
link: www.aelshafee.net/HAS01.
V. FUTURE WORK
The following point presents the suggested future work for
implemented prototype:
Implements more hardware interface modules, and modify
server application software to handle them.
Modify hardware interface module to be able to
communicates with sensors and actuators that use wireless
technologies like X10, Zigbee, etc.
By doing this system will increase system mobility,
configurable, and scalability.
More intelligent should be added to hardware modules to
make them capable to take decision according to triggered
alarms. Without referring to server for each event and action.
That will increase the response time of the system. While
hardware interface module reports server with events and
actions on pre-programmed intervals.
Replace the WiFly WiFi module with more reliable and
stable WiFi module, to increase system reliability.
VI. CONCLUSION
This paper proposes a low cost, secure, ubiquitously
accessible, auto-configurable, remotely controlled solution.
The approach discussed in the paper is novel and has
achieved the target to control home appliances remotely using
the WiFi technology to connects system parts, satisfying user
needs and requirements.
WiFi technology capable solution has proved to be controlled
remotely, provide home security and is cost-effective as
compared to the previously existing systems.
Hence we can conclude that the required goals and
objectives of home automation system have been achieved.
The system design and architecture were discussed, and
prototype presents the basic level of home appliance control
and remote monitoring has been implemented.
Finally, the proposed system is better from the scalability
and flexibility point of view than the commercially available
home automation systems.
ACKNOWLEDGEMENT
This paper is based on B.Sc. graduation project
accomplished at Ahram Canadian University, Faculty of
Computer Science and IT, 2011. Graduation project was
supervised by the 1st author, and team is presented by the 2nd
author.
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Fig. 8 Overall interface
Fig. 9 Automation interface (system configuration)
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