IJETT-V4I4P294

International Journal of Engineering Trends and Technology (IJETT) - Volume4Issue4- April 2013

ISSN: 2231-5381 http://www.ijettjournal.org Page 972

Energy Efficient Micro controller Based Automation System M.AARTHI#1, M.ANIL KUMAR *2

#Department of Electronics and communications Engineering, K L University Vaddeswaram, Guntur, AP, India

*Asst Professor Department of Electronics and communications Engineering, K L University

Vaddeswaram, Guntur, AP, India Abstract with advancement of technology the ease with which we are getting accesses to electrical products is increasing and with that the power consumption is also increasing. Most of the power is being wasted because we forget to switch of a light or a fan when it is not required. while in a household the wastage due to this is small imagine a visitor's for about 200 people where the attendant forgot to switch of the lights and fans. They would be running all the night wasting a lot of power. So in this paper talks about a system which effectively shuts down the basic appliance when they are not required the basic definitions needed to understand the Project better. Keywords-Automation, 8051 micro controller, LDR, LED, ADC, Relays, LCD display, Sensors, Stepper motor, PIR sensor

I. INTRODUCTION

With advancement of technology things are becoming simpler and easier for us. Automation is the use of control systems and information technologies to reduce the need for human work in the production of goods and services. In the scope of industrialization, automation is a step beyond mechanization. Whereas mechanization provided human operators with machinery to assist them with the muscular requirements of work, automation greatly decreases the need for human sensory and mental requirements as well. Automation plays an increasingly important role in the world economy and in daily experience.

Automatic systems are being preferred over manual system. Through this project we have tried to show automatic control of house appliance as a result

of which power is saved II. NEED OF AUTOMATION

Let us see why automated systems are being used a) An automated device can replace good amount of human working force, moreover humans are more prone to errors and in intensive conditions the probability of error increases whereas, an automated device can work with diligence, versatility and with almost zero error. Replacing human operators in tasks that involve hard physical or monotonous work. Replacing humans in tasks done in dangerous environments (i.e. fire, space, volcanoes, nuclear facilities, underwater, etc). Performing tasks that are beyond human capabilities of size, weight, speed, endurance, etc. b) Economy improvement: Automation may improve in economy of enterprises, society or most of humankind. For example, when an enterprise that has invested in automation technology recovers its investment, or when a state or country increases its income due to automation like Germany or Japan in the 20th Century.



III.SYSTEM ARCHITECTURE

Fig.1 System Architecture

A.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. These change pulses are

what is detected. In order to shape the FOV, i.e. Field Of View of the sensor, the detector is equipped with lenses in front of it. The lens used here is inexpensive and lightweight plastic materials with transmission characteristics suited for the desired wavelength range. To cover much larger area, detection lens is split up into multiple sections, each section of which is a Fresnel lens. Fresnel lens condenses light. Providing a larger range of IR to the sensor it can span over several tens of degree width. Thus total configuration improves immunity to changes in background temperature, noise or humidity and causes a shorter settling time of the output after a body moved in or out the FOV.

Fig.2 PIR Sensor output waveform B .Power Supply To power up any electronic circuit we require power supply system which provides required power for the system to operate. Here we need power supply for driving MCU,PIR sensor,Temperature sensor and ADC.We generally get 230Vac signal as mains supply in most of the homes.we take this 230Vac signal and convert it into 5Vdc signal to drive our components.To convert AC to DC we can use either



linear power supply conversion or SMPS(switch mode power supply).But using SMPS system gives us very good conversion efficiency of about 80%.Here we will briefly give a overview about basic components used SMPS power supply design Transformer Rectifier Input filter PWM controller Regulator 1) Transformer: This is a very important component in power supply design.it is used for steeping down the i/p voltage and also provide galvanic isolation.Depending on turn ratio used in transformer we can determine the step down ratio.transformer takes ac input and gives ac output. 2) Rectifier: Rectifier is a circuit which is used to convert ac to dc. After transformer steps down the input mains voltage we pass it through rectifier to convert it to DC.we used 4 diodes in bridge configuration for rectification. 3) Input filter: After rectification we obtain dc supply from ac but it is not pure dc it may have some ac ripples .To reduce these ripples we use filters.generally a capacitor is used. 4) PWM controller:The dc output we got is chopped using a high frequency switching circuit(PWM switch)which switches according to it's duty cycle. PWM controller takes feedback from final DC output and depending on that it modifies the duty cycle for the turn on and turn off periods.Now that we got a high frequency signal from the PWM switch we pass it through a transformer and then the AC output obtained is converted to DC using rectifiers. 5) Regulator: Regulator is a device which provides constant output Voltage with varying input voltage. There are two types of regulators- (a) Fixed voltage regulator (b) Adjustable regulator We have used fixed voltage regulator LM78XX last two digits signify output voltage. The voltage for our

system is 5V that is why we have used 7805 regulator which provides 5V from 12V dc. C. Temperature Sensor LM35: This is temperature sensor IC rated for full -55 to + 150C temperature range. This is a transducer IC that takes voltage input and gives a voltage output proportional to the ambient temperature. +VS pin is connected to the output pin of LM7805 and the VOUT pin is connected to one of the analog input channels available on MCU. IV. WORKING LDR output, PIR sensor output and temperature sensor output is given to the analog to digital converter.

Fig.3 software flowchart



The outputs from ADC is scanned by micro controller in a cyclic manner from its input ports and compared with the predetermined values stored in micro controller.First the MCU scan's PIR Sensor port and compares its value with 3v digital value. If it is greater than that it means there is person present in room and it should switch on the lights and fans. But if there is enough light in room due to the natural sun light, it is a waste of power to switch on light so, it first checks for brightness in the room with the help of LDR. LDR means light dependent resistor. As the light falling it on increases its Resistance decreases and vice-verse.LDR is connected in series with a fixed value resistor and a voltage of +5v is applied to the combination. Voltage across LDR is given to ADC and then imputed to MCU by experimenting with different intensities of light we can have a voltage value at which we want to turn on the light depending on our needs. We can use this voltage value as reference value in MCU code above which the light should be turned on. Now that it decided about light it sees weather to turn on the cooling system such as fan. It takes the input from a temperature sensor such as LM35 and checks weather the temperature value it obtained is above the internally stored value. If it greater it will turn on the cooling system and if it is below it doesn't .we can use internal storage value as 20c. V. IMPROVEMENTS

By doing some small modification's in the code we can enhance this project If the temperature sensed by the temperature

sensor is very high like 45c if most probably means some thing nearby is on fire. so we can add a buzzer to our circuit we would sound the alarm above 45c.

We are considering only cooling system to turn on but if we have a heating system too we can turn it on but setting a upper limit in the MCU below

which it should turn on the heating system VI.CONCLUSION This is a very low cost system for automating many home appliances to save a lot of power by turning them off when they are not required.It is also easy to add more number of PIR sensor module to already existing circuit to increase range of operation But the main drawback of this is that PIR sensor is very sensitive.It can detect IR radiations from our pet's like dog's and cat's and are also sensitive to exposure from direct sunlight and direct wind from heaters and air conditioners

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[2] "U.S. Patent 613809: Method of and apparatus for controlling

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[3] William C. Mann (ed.) Smart technology for aging, disability and

independence : the state of the science, John Wiley and Sons, 2005 0- 471-69694-3, pp. 34-66

[4] M. Moghavvemi and C.S. Lu, "Pyroelectric infrared sensor for intruder detection," in Proc. TENCON 2004 Conf., pp. 656-659.

[5] Schneider Electric. PDL PIR Sensor Technical Guide. [Online]. Available: http://www.pdlglobal.comlbrochures/PIRSensorsTechnicalBooklet.pdf.

[6] http://www.ladyada.net/learn/sensors/pir.html [7] http://en.wikipedia.org/wiki/Passive_infrared_sensor [8]Zamshed Iqbal Chowdhury, Masudul Haider Imtiaz,Muhammad Moinul Azam, Mst. Rumana Aktar Sumi and Nafisa Shahera Nur."Design and Implementation of Pyroelectric Infrared Sensor Based Security System Using Microcontroller",Proceeding of the 2011 IEEE Students' Technology Symposium,lIT Kharagpur,14th-16th Jan, 2011.

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IJETT-V4I4P294