21-06-2012, 04:12 PM
Design and Implementation of Pyroelectric Infrared Sensor Based Security System Using Microcontroller
INTRODUCTION
Security and safety is one of the most talked of topics in
almost every facet like surveillance, industrial applications,
offices, and in general, in smart environments. To secure it
against theft, crime, fire, etc. a powerful security system is
required not only to detect but also pre-empt hazards.
Conventional security systems use cameras and process large
amounts of data to extract features with high cost and hence
require significant infrastructures. This paper proposes a PIR
sensor based low cost security system for home applications in
which Passive Infrared (PIR) sensor has been implemented to
sense the motion of human through the detection of infrared
radiated from that human body. PIR device does not emit an
infrared beam but passively accepts incoming infrared
radiation. Fig. 1 shows the block diagram of the system.
RELATED WORKS
Today' s indoor security systems built with various sensors
such as ultrasonic detectors, microwave detectors, photoelectric
detectors, infrared detectors etc. Each of these systems
has its own limitations. As an example, photo-electric beam
systems detect the presence of an intruder by transmitting
visible or infrared light beams across an area, where these
beams maybe obstructed. But the drawback lies within it if the
intruder is aware of the presence of this system. Despite of
having strong dependence on surrounding environmental
status, pyroelectricity has become a widely used detection
parameter because of simplicity and privilege of interfacing to
the digital systems. N ow, it is extensively used for intruder
detection, smart environment sensing, and power management
applications. Several works have been conducted in various
applications. Intelligent fireproof and theft-proof alarm system
[ 1], GSM (Global System for Mobile) network based home
safeguard system [2], human tracking system [3] and intruder
detection systems [4] are some notable works done previously
based on pyroelectricity sensing technique.
PIR SENSOR
PIR is basically made of Pyroelectric sensors to develop an
electric signal in response to a change in the incident thermal
radiation. Every living body emits some low level radiations
and the hotter the body, the more is emitted radiation.
Commercial PIR sensors typically include two IR-sensitive
elements with opposite polarization housed in a hermetically
sealed metal with a window made of IR-transmissive material
(typically coated silicon to protect the sensing element). When
the sensor is idle, both slots detect the same amount of IR, the
ambient amount radiated from the room or walls or outdoors.
When a warm body like a human or an animal passes by, it fIrst
intercepts one half of the PIR sensor which causes a positive
differential change between the two halves. When the warm
body leaves the sensing area, the reverse happens, whereby the
sensor generates a negative differential change.
SOFTWARE
The whole system is built around a MCU. MCU requires to be
burned with software written for specific applications. The
code is written using ASSEMBLY language and compiled
using MPLAB. MPLAB generated a hex file which is burned
using a burner into the IC. This section demonstrates the
flowchart of the software which helps to visualize the coding
steps which is shown in the Fig. 7. At the beginning of the
program, external interrupt of MCU is disabled in software.
Therefore, any signal input on the pin RBO cannot generate
interrupt. Then, MCU looks for the switch whether it is closed
or open. When the switch is open the signal is LOW and when
the switch is closed, the signal is HIGH on pin RBO. If the
signal is LOW, MCU repeatedly checks for the switch status.
When the signal gets HIGH, MCU converts the analog signal
from the temperature sensor to the binary equivalent and
checks repeatedly if the temperature of the surrounding is
greater or equal to 15° Celsius.
FUTURE WORK & CONCLUSION
In this security system PIR sensor has been used which is
low power, and low cost, pretty rugged, have a wide lens
range, and are easy to interface with. This security system can
be implemented in places like home, office, shop etc. The
sensitivity range for detecting motion of the system is about 3
to 4 feet. It can be raised up to 20 feet through careful use of
concentrating optical lenses as future development. In addition
to this, this system can be equipped with glass break detectors
to enhance the level of protection. Use of multi-sensor data
fusion and complex algorithm can be used to increase the
effective FOV for larger spaces. In order to enhance the
location accuracy and to enhance the method of processing the
PIR sensor signal, use of more advanced techniques such as
probabilistic theories and soft computing is left open for the
future.
INTRODUCTION
Security and safety is one of the most talked of topics in
almost every facet like surveillance, industrial applications,
offices, and in general, in smart environments. To secure it
against theft, crime, fire, etc. a powerful security system is
required not only to detect but also pre-empt hazards.
Conventional security systems use cameras and process large
amounts of data to extract features with high cost and hence
require significant infrastructures. This paper proposes a PIR
sensor based low cost security system for home applications in
which Passive Infrared (PIR) sensor has been implemented to
sense the motion of human through the detection of infrared
radiated from that human body. PIR device does not emit an
infrared beam but passively accepts incoming infrared
radiation. Fig. 1 shows the block diagram of the system.
RELATED WORKS
Today' s indoor security systems built with various sensors
such as ultrasonic detectors, microwave detectors, photoelectric
detectors, infrared detectors etc. Each of these systems
has its own limitations. As an example, photo-electric beam
systems detect the presence of an intruder by transmitting
visible or infrared light beams across an area, where these
beams maybe obstructed. But the drawback lies within it if the
intruder is aware of the presence of this system. Despite of
having strong dependence on surrounding environmental
status, pyroelectricity has become a widely used detection
parameter because of simplicity and privilege of interfacing to
the digital systems. N ow, it is extensively used for intruder
detection, smart environment sensing, and power management
applications. Several works have been conducted in various
applications. Intelligent fireproof and theft-proof alarm system
[ 1], GSM (Global System for Mobile) network based home
safeguard system [2], human tracking system [3] and intruder
detection systems [4] are some notable works done previously
based on pyroelectricity sensing technique.
PIR SENSOR
PIR is basically made of Pyroelectric sensors to develop an
electric signal in response to a change in the incident thermal
radiation. Every living body emits some low level radiations
and the hotter the body, the more is emitted radiation.
Commercial PIR sensors typically include two IR-sensitive
elements with opposite polarization housed in a hermetically
sealed metal with a window made of IR-transmissive material
(typically coated silicon to protect the sensing element). When
the sensor is idle, both slots detect the same amount of IR, the
ambient amount radiated from the room or walls or outdoors.
When a warm body like a human or an animal passes by, it fIrst
intercepts one half of the PIR sensor which causes a positive
differential change between the two halves. When the warm
body leaves the sensing area, the reverse happens, whereby the
sensor generates a negative differential change.
SOFTWARE
The whole system is built around a MCU. MCU requires to be
burned with software written for specific applications. The
code is written using ASSEMBLY language and compiled
using MPLAB. MPLAB generated a hex file which is burned
using a burner into the IC. This section demonstrates the
flowchart of the software which helps to visualize the coding
steps which is shown in the Fig. 7. At the beginning of the
program, external interrupt of MCU is disabled in software.
Therefore, any signal input on the pin RBO cannot generate
interrupt. Then, MCU looks for the switch whether it is closed
or open. When the switch is open the signal is LOW and when
the switch is closed, the signal is HIGH on pin RBO. If the
signal is LOW, MCU repeatedly checks for the switch status.
When the signal gets HIGH, MCU converts the analog signal
from the temperature sensor to the binary equivalent and
checks repeatedly if the temperature of the surrounding is
greater or equal to 15° Celsius.
FUTURE WORK & CONCLUSION
In this security system PIR sensor has been used which is
low power, and low cost, pretty rugged, have a wide lens
range, and are easy to interface with. This security system can
be implemented in places like home, office, shop etc. The
sensitivity range for detecting motion of the system is about 3
to 4 feet. It can be raised up to 20 feet through careful use of
concentrating optical lenses as future development. In addition
to this, this system can be equipped with glass break detectors
to enhance the level of protection. Use of multi-sensor data
fusion and complex algorithm can be used to increase the
effective FOV for larger spaces. In order to enhance the
location accuracy and to enhance the method of processing the
PIR sensor signal, use of more advanced techniques such as
probabilistic theories and soft computing is left open for the
future.