Smart Window Blind Control System M. Bhuiyan1, D. A. Firdhaus2 and Kh. Arif Shahriar3

1Department of Electrical and Electronic Engineering, Northern University Bangladesh, Dhaka, Bangladesh. 2Department of Mechatronics Engineering, International Islamic University Malaysia, Kuala Lumpur, Malaysia.

3Department of Electrical and Electronic Engineering, Northern University Bangladesh, Dhaka, Bangladesh. 1bmoinul1972@yahoo.co.jp, 2dzulasyraff@gmail.com and 3arif.sjn@gmail.com

Abstract—This paper presents a smart window blind system

to control correct amount of sunlight needed to shine a room. The system can be operated in either manual or automatic mode. The manual mode activates two push buttons for the tilting control. For automatic mode, the blind will open or close, depending on the amount of light that is shining through the window. The blind will be closed fully when the sensor level is below 200, and will be opened at 50% when the value is above 800. If the sensor level is between 200 and 800, the blind level will be fully opened. A servo motor is attached to the blind’s controlling shaft for the actuation of tilting. The results show that the system is usable and can be used commercially in office and home.

Keywords— Venetian blinds, glare, ambient light sensor, IR remote controller, servo motor.

I. INTRODUCTION Optimum utilization of daylight, maintaining proper indoor

lighting intensity and glare protection are some of the challenges that need to be solved to ensure a comfortable ambience at homes and offices. A window blind gives a high level of user convenience in terms of heat protection and also prevents glare related problems. Direct emission of sunlight on the furniture will eventually damage them. Automation of the window blind allows the user to protect the valuable furniture from direct sunlight. The controlling system that regulates the blind opening and closing during day time can either be computer based or microcontroller based [1] [2].

Apart from that, when the sun goes down, the windows become transparent and the private business becomes visible to anyone passing by. The ability to automatically close the blinds after sunset can be achieved by using ambient light sensor.

In addition, the automation of window blind would save energy consumption and will ensure the sustainability of the environment [3]. Closing the blind automatically during the hot weather will prevent the hot sun rays from heating up the room and thus will reduce the usage of air conditioners. Likewise, when it is cold outside, closing the blind can help to trap the valuable heat inside. If automated and controlled correctly, solar blind systems can reduce energy requirements by 10 percent.

The blind systems are used to filter completely or partially the daylight entering into the room. To prevent glare sources from impacting the occupancy area, some constraints on working state of the shading device are defined. The working state of a venetian blind is described by the descent of the blind and the angle of the slats. To counteract a glaring ray, a minimum descent (denoted by 푑 ) and a minimum angle of

slats (denoted by 휃 ) are imposed to the blind system [4]. It is as shown in Fig.1.

Fig.1: Venetian blind position for glare rejection. The health and safety of user should never be compromised

in order to reduce costs. The blind should ensure the privacy of the user staying inside the room. For example, during night, the blinds must be closed and opaque so that people from outside are unable see what is happening inside the room. The smart window blind should be built to have the longest possible useful life and require minimum repairing and maintenance. In case of damage, the replacement parts should be easily available and the repairing process should be easy for the user.

The position of the sun will affect the smart window design. At early morning and late afternoon, the light level is usually ambient and hence the blind should totally open. At mid-day, the sunlight will usually be intense enough to cause glare to the user and affect his/her vision. Then, the blinds should tilt down and allow small amount of light into the room. The blind should fully close at night in order to protect the privacy of the user.

A lot of researches have been conducted on window blind control. Chen et al. presented the venetian blind control using fuzzy neural network for indoor day lighting [5]. Solar powered smart blind system was proposed by Herrera et al. [6]. Kim et al. have conducted an extensive experimental study to evaluate the environmental performance of automated venetian blind [7]. As the Microcontroller Unit (MCU) is currently popular in designing various automatic and autonomous systems [8] [9] [10], this research uses the Arduino microcontroller unit for designing the motion control system of the window blind.

II. SYSTEM ANALYSIS The smart window blind uses the concept of wireless

communication which is a method of controlling the tilting of the blind with a motor without direct wiring. The motor

connected to the controlling shaft and the gear provides balance and gripping to the shaft that controls the blind’s tilting angle. Fig.2 shows the flow-chart of the algorithm of the smart window blind system.

Fig.2: Flow-chart of the algorithm for operation of the smart window blind system

The user can choose one from two modes - either automatic

or manual. The automatic mode uses sensor attached at the front of the window. The sensor will detect the intensity of light and automatically tilts the blinds to an appropriate angle. On the other hand, the manual mode provides a direct control from the user via a handheld remote controller. The user will tilt the blind based on his/her own preference. This mode is preferred whenever automatic mode can’t provide optimum amount of lighting into the room.

The code is written in C programming language. The algorithm is comprised of a process that monitors the digital values of the controls on the switch box. The system monitors a push button for the mode selection - either automatic or manual. The rocker switch is used as the primary input to the system. If the switch sends out binary 0, the system will be activated in automatic mode while sending out binary 1 will cause the system to operate in manual mode. The mode information will be displayed on LCD to let the user know the current state of the blind.

In automatic mode, the optical sensor returns an analog value ranging from 0 to 1023. The value 0 indicates the darkest scenario while 1023 indicates the brightest. Three ranges of analog values which represent the ambient, bright and dark environment will be declared in the microcontroller.

Every second, a new value is read from the optical sensor and based on the range to which value belongs, the servo motor is rotated in the appropriated direction and revolution that has been set in the program.

On the other hand, in manual mode, some sets of binary data will be declared to represent specific commands. Then, the signal send out by infrared transmitter will be detected by the receiver that has been connected to the microcontroller. The signal received will be decoded by the microcontroller

into a binary data. These binary data will be compared to the default data in the programming and the actuator will carry out the command.

III. DESING AND CALIBRATION Smart window blind mainly uses hardware for the design of

the controller. The system also uses a rocker switch for user selection of desired control mode. Two types of controller are used which are infrared handheld remote control and ambient light sensor.

Fig.3: Hardware model of the Smart Window Blind System

Basically these two devices act as receiver. They will receive signal from the sources or transmitter. This signal will then be sent to the microcontroller which will send out the command to actuate the motor. The blind’s tilting will be proportional to the total rotation made by the motor. Connections between the hardware components have been illustrated in Fig.3.

A. Smart Window Blind Design A servo motor will be attached directly to the controlling

shaft. The angles of tilting were determined by the rotational number of the motor. The microcontroller unit, infrared receiver and the sensor will be placed in a controller unit.

Fig.4: Smart window blind design sketched in Solid Work

The system is powered by 6V power supply. LCD would let the user know the current mode of the system - automatic or

manual. A rocker switch is used for the selection of desired operating mode of the blinds. The tilting angle of the blinds will correspond to the rotational number of the servo. Fig.5 shows the whole connectivity among the different components of the control system.

Fig.5: Designed control system circuit sketched by Fritzing

B. Smart Window Blind Design Fig.6 shows the configuration for the calibration of the

ambient light sensor. This testing is to determine whether the sensor can control the activation of the LED based on the amount of light falling on the sensor. A coding structure has been sketched via Arduino software which gives instructions to the LED to turn on whenever the light level is above 200 and off for light level below 200. Finally, a light source is used to vary the amount of light falling on the sensor.

Fig.6: Configuration for the calibration of sensor

The test shows that the sensor can control the activation of LED as expected. When the sensor is exposed to the dark room, the LED is off. LED is on whenever the lamp is directed by the sensor. The calibration of IR remote controller has been done by sketching a set of coding into Arduino which gives instruction to LED to turn on whenever button ‘A’ is pushed and turn off when button ‘B’ is pushed. Fig.7 shows the configuration for the calibration of IR remote controller.

Fig.7: Configuration for the calibration of IR remote controller kit

C. Calibration of Ambient Light Sensor The analog values of sunlight in a day have to be known so

that the ranges of light level can be designed. The light sensor has been set up and the analog values of light in a day has been recorded.

Table 1: Analog Readings of Light Intensity by Sensor on 1/5/2013

The light sensor has been exposed to sunlight for a whole day and the analog reading for every hour was recorded. Value 0 indicates that the brightness level is at lowest while 1023 indicates the brightness level is at the highest.

Fig.6: Graph of light levels over time

Based on the calibration, the total system settings has been declared and integrated to the main system. Table 2 shows the configuration for automatic mode.

Table 2: Automatic mode system configuration

Normally, the sun rises at 7.00 am and the brightness level is ambient. Thus, the blind should fully open and allow the light into the room. When the time is 11.00 am, the sun is positioned almost at the peak of its trajectory. Then, the

surrounding will be brightest and glaring effect will rise. At this moment, the blinds should allow only some amount of light into the room by opening at 45 degree. Later, at night, there is no sunlight and the outside is dark. The inside part of the room will be transparent to the outsider. For privacy concern, the blind will be fully closed.

D. Calibration of IR Remote Controller Similar to ambient light sensor, each button of the IR

remote controller was represented by analog values. These analog values are converted into decimal and hexadecimal. A simple configuration has been set up to extract the analog values of the buttons.

Table 3: Codes of IR remote controller

Table 4 shows the configuration for manual mode which is

integrated to the main system.

Table 4: Manual mode system configuration

IV. RESULT AND ANALYSIS

A. Development of Smart Window Blind Prototype Refer to Fig.7 (a); the black frame represents the room’s

window and the orange box represents the main processing unit of the system. The controlling unit has been put at the lower front part of the blind so that the user can easily communicate with the system.

Most of the electrical components were placed around the controlling unit box as shown in Fig.7 (c) so that it is easier to debug the system. The connection among the components also has been compiled at the inner part of the controlling unit because to avoid high temperature, high humidity and other disturbance that may affect the system performance. Both input and output units were connected to the controlling unit. An LCD has been attached to the controlling unit as to inform the user about the current operating mode of the system; either automatic or manual.

Fig.7: Smart window blind prototype: (a) Final prototype,

(b) Controller unit, (c) Inside of controller unit

Fig.7 (b) shows the input units of the smart window blind system. A rocker switch has been fitted to the front part of the controlling unit so that the user can easily achieve and choose an operating mode. The rocker switch has markings of “auto” and “manual” for convenience of the user. An IR remote and receiver have also been placed at the front part of the system to make the interaction between the remote and the receiver smooth without any barriers.

Fig.8: Outputs of smart window blind system (a) Ambient light

sensor on the frame, at the back of window blind, (b) Servo directly attached to tilt-controlling shaft

As for auto mode, the sensor has been fitted at the back part

of the system as shown in Fig.8(a), which also symbolizes that the sensor would face up to the outer part of the room and the sunlight. The light falling on the window will be detected and converted by the sensor as the input of the system. Servo motor is attached directly to the controlling shaft for the actuation of tilting as shown in Fig.8 (b).

B. Testing and Observation Lab test is conducted, shown in Fig.9, as to observe whether

the blinds can cooperate with the three states when it is operating in automatic mode. At first, all sources of lights in the lab have been turned off. As a result, the servo rotated and the blind was fully closed. This configuration is to imitate darkness. Next, the light bulb of the lab has been switched on as to imitate the environment with ambient lighting. Then, the blind was fully opened by itself. Lastly, a lab lamp has been used as a source for the direct lighting to the window. Since the light intensity was too high, the blind then changes to 45 degree opening as predicted.

Fig.9: Automatic mode lab test: (a) Auto mode activated, (b) Light sensor on the window, (c) Blind closed when dark, (d) Blind fully

opened when ambient, and (e) Blind opened to 45 degree when bright

Manual mode also needs to be tested as shown in Fig.10. In this mode, the blind will open up and close down based on the user preference regardless of the outside brightness level. The testing was carried out by pressing any one of the two buttons that have been set up for controlling of the system. Button ‘A’ will rotate the motor counterclockwise and open up the blind while button ‘B’ will rotate the motor clockwise and close down the blind.

Fig.10: Manual mode lab test: (a) Manual mode activated, (b)

Interaction between IR remote unit and receiver, and (c) Servo rotates based on which button was pushed

In addition, the selection of operation in automatic and

manual mode was determined by the activation of the rocker switch. The LCD was displaying the information about the current state of the system; automatic or manual mode.

C. Real Time Behavior Malaysia is a country that has equatorial climate with high

temperatures and wet months throughout the years. A testing has been carried out by exposing the blind to the sunlight. For a whole day, the light level detected by the sensor for each hour is recorded and the opening of the blind is observed. The testing has been done on both dry and rainy days. Then, the effectiveness of the blind adjusting the opening by itself in the real situation can be confirmed.

The first test was done on a dry and high temperature day. The blind’s opening and closing durations were observed. The data have been summarized in Fig.11.

Fig.11: Blind's opening on sunny day

From 7 pm to 7 am, the brightness level is very low and people from outside can see what’s happening inside the room. Thus, the blind was fully closed for the security purposed. Then, after 7 am, it is sunrise, the outside was bright and the blind starts to open up. The opening was at maximum to allow all the light into the room. However, at 10 am the sun is positioned at peak, high amount of light falls on the window and produces glare effect to the user inside of the room. The blind only opened to half of the maximum opening to allow appropriate amount of light into the room. Finally, at 7 pm as the outside was getting dark, the blind becomes fully closed.

Then, the second test was done to observe the opening of the blind on the wet, rainy day. Basically, on that day, the weather was rainy and the outdoor brightness levels detected by the sensor were either at medium or low. Fig.12 shows the light level throughout the rainy day and the effect on the blind’s opening. The blind was either fully opened or fully closed since the day was gloomy and only small and moderate amount of light can be detected by the sensor.

Fig.12: Blind's opening on rainy day

From these real time tests, the smart window blind system has been proved to work properly and can adapt to the real situation. The system could tilt the blind based on the amount of light falling on the window. During the dry season, the blind could reject the glares produced by the sunlight on the brightest day by tilting to half of the maximum opening and provide sufficient lighting to the room while during the rainy

season, the blind provides a good privacy as it gets dark outside and most people are at their home.

V. CONCLUSION AND RECOMMENDATION A smart window blind system has been developed and

designed so that it can automatically adjust to the amount of sunlight shining through a window. For the automatic mode, the blinds adjusted the tilting angle of the slat based on the light intensity that has been programmed into the microcontroller. When ambient lighting falls on the window, the servo would rotate counterclockwise to fully open the blinds while when there is very low amount of light, the servo would rotate clockwise to fully close the blinds.

The smart window blind system has been designed based on the reviewing the basic concept and mechanism of common window blind. The components that are used for the construction of the prototype are analyzed for selection of the best materials and specifications that are suitable for the load and optimizing the budget. Originally, the servo should be integrated into the rail of the blind so that the shaft would not have to be coupled together as shown in the design. When there is too much ambient light and not enough direct light to accurately detect by the sensor, inaccuracies would be produced and as a result, the microcontroller would interpret it wrongly.

In addition, for future improvements, the servo should be directly integrated into the main frame of the blind and the use of the blind’s shaft can be eliminated. Electrical energy also can be substituted with a renewable, clean energy such as replacing the use of batteries with solar energy.

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