智能家居红外传感器毕业论文中英文资料外文翻译文献

1 毕业论文中英文资料外文翻译文献毕业论文中英文资料外文翻译文献 A Pyroelectric Infrared Sensor based Indoor Location Aware System for the Smart Home Suk Lee Member IEEE Kyoung Nam Ha Kyung Chang Lee Member IEEE Abstract Smart home is expected to offer various intelligent services by recognizing residents along with their life style and feelings One of the key issues for realizing the smart home is how to detect the locations of residents Currently the research effort is focused on two approaches terminal based and non terminal based methods The terminal based method employs a type of device that should be carried by the resident while the non terminal based method requires no such device This paper presents a novel non terminal based approach using an array of pyroelectric infrared sensors PIR sensors that can detect residents The feasibility of the system is evaluated experimentally on a test bed Key words smart home location based service pyroelectric infrared sensor PIR sensor location recognition algorithm I INTRODUCTION There is a growing interest in smart home as a way to offer a convenient comfortable and safe residential environment 1 2 In general the smart home aims to offer appropriate intelligent services to actively assist in the resident s life such as housework amusement rest and sleep Hence in order to enhance the resident s convenience and safety devices such as home appliances multimedia appliances and internet appliances should be connected via a home network system as shown in Fig 1 and they should be controlled or monitored remotely using a television TV or personal digital assistant PDA 3 4 2 Fig 1 Architecture of the home network system for smart home Especially attention has been focused on location based services as a way to offer high quality intelligent services while considering human factors such as pattern of living health and feelings of a resident 5 7 That is if the smart home can recognize the resident s pattern of living or health then home appliances should be able to anticipate the resident s needs and offer appropriate intelligent service more actively For example in a passive service environment the resident controls the operation of the HVAC heating ventilating and air conditioning system while the smart home would control the temperature and humidity of a room according to the resident s condition Various indoor location aware systems have been developed to recognize the resident s location in the smart home or smart office In general indoor location aware systems have been classified into three types according to the measurement technology triangulation scene analysis and proximity methods 8 The triangulation method uses multiple distances from multiple known points Examples include Active Badges 9 Active Bats 10 and Easy Living 11 which use infrared sensors ultrasonic sensors and vision sensors respectively The scene analysis method examines a view from a particular vantage point Representative examples of the scene analysis method are MotionStar 12 which uses a DC magnetic tracker and RADAR 13 which uses IEEE 802 11 wireless local area network LAN Finally the proximity method measures nearness to a known set of points An example of the proximity method is Smart Floor 14 which uses pressure sensors Alternatively indoor location aware systems can be classified according to the need for a terminal that should be carried by the resident Terminal based methods such as Active Bats do not recognize the resident s location directly but perceive the location of a device carried by the resident such as an infrared transceiver or radio 3 frequency identification RFID tag Therefore it is impossible to recognize the resident s location if he or she is not carrying the device In contrast non terminal methods such as Easy Living and Smart Floor can find the resident s location without such devices However Easy Living can be regarded to invade the resident s privacy while the Smart Floor has difficulty with extendibility and maintenance This paper presents a non terminal based location aware system that uses an array of pyroelectric infrared PIR sensors 15 16 The PIR sensors on the ceiling detect the presence of a resident and are laid out so that detection areas of adjacent sensors overlap By combining the outputs of multiple PIR sensors the system is able to locate a resident with a reasonable degree of accuracy This system has inherent advantage of non terminal based methods while avoiding privacy and extendibility maintenance issues In order to demonstrate its efficacy an experimental test bed has been constructed and the proposed system has been evaluated experimentally under various experimental conditions This paper is organized into four sections including this introduction Section II presents the architecture of the PIR sensor based indoor location aware system PILAS and the location recognition algorithm Section III describes a resident detection method using PIR sensors and evaluates the performance of the system under various conditions using an experimental test bed Finally a summary and the conclusions are presented in Section IV II ARCHITECTURE OF THE PIR SENSOR BASED INDOOR LOCATION AWARE SYSTEM A Framework of the smart home Given the indoor environment of the smart home an indoor location aware system must satisfy the following requirements First the location aware system should be implemented at a relatively low cost because many sensors have to be installed in rooms of different sizes to detect the resident in the smart home Second sensor installation must be flexible because the shape of each room is different and there are obstacles such as home appliances and furniture which prevent the normal operation of sensors The third requirement is that the sensors for the location aware system have to be robust to noise and should not be affected by their surroundings This is because the smart home can make use of various wireless communication methods such as wireless LAN or radio frequency RF systems which produce electromagnetic noise or there may be significant changes in light or temperature that can affect sensor performance Finally it is desirable that the system s accuracy is adjustable according to room types Among many systems that satisfy the requirement the PIR sensor based system has not 4 attracted much attention even though the system has several advantages The PIR sensors which have been used to turn on a light when it detects human movement are less expensive than many other sensors In addition because PIR sensors detect the infrared wavelengthemitted from humans between 9 4 10 4 m they are reasonably robust to their surroundings in terms of temperature humidity and electromagnetic noise Moreover it ispossible to control the location accuracy of the system by adjusting the sensing radius of a PIR sensor and PIR sensors are easily installed on the ceiling where they are not affected by the structure of a room or any obstacles Figure 2 shows the framework for the PILAS in a smart home that offers location based intelligent services to a resident Within this framework various devices are connected via a home network system including PIR sensors room terminals a smart home server and home appliances Here each room is regarded as a cell and the appropriate number of PIR sensors is installed on the ceiling of each cell to provide sufficient location accuracy for the location based services Each PIR sensor attempts to detect the resident at a constant period and transmits its sensing information to a room terminal via the home network system Fig 2 Framework of smart home for the PILAS Consequently the room terminal recognizes the resident s location by integrating the sensor information received from all of the sensors belonging to one cell and transmits the resident s location to the smart home server that controls the home appliances to offer location based 5 intelligent services to the resident Within this framework the smart home server has the following functions 1 The virtual map generator makes a virtual map of the smart home generating a virtual map and writes the location information of the resident which is received from a room terminal on the virtual map writing the resident s location Then it makes a moving trajectory of the resident by connecting the successive locations of the resident tracking the resident s movement 2 The home appliance controller transmits control commands to home appliances via the home network system to provide intelligent services to the resident 3 The moving pattern predictor saves the current movement trajectory of the resident the current action of home appliances and parameters reflecting the current home environment such as the time temperature humidity and illumination After storing sufficient information it may be possible to offer human oriented intelligent services in which the home appliances spontaneously provide services to satisfy human needs For example if the smart home server knows that the resident normally wakes up at 7 00 A M and takes a shower it may be possible to turn on the lamps and some music In addition the temperature of the shower water can be set automatically for the resident B Location recognition algorithm In order to determine the location of a resident within a room an array of PIR sensors are used as shown in Fig 3 In the figure the sensing area of each PIR sensor is shown as a circle and the sensing areas of two or more sensors overlap Consequently when a resident enters one of the sensing areas the system decides whether he she belongs to any sensing area by integrating the sensing information collected from all of the PIR sensors in the room For example when a resident enters the sensing area B sensors a and b output ON signals while sensor c outputs OFF signal After collecting outputs the algorithm can infer that the resident belongs to the sensing area B According to the number of sensors and the arrangement of the sensors signaling ON the resident s location is deter mined in the following manner First if only one sensor outputs ON signal the resident is regarded to be at the center of the sensing area of the corresponding sensor If the outputs of two adjacent sensors are ON the resident s location is assumed to be at the point midway between the two sensors Finally if three or more sensors signal ON the resident is located at the centroid of the centers of the corresponding sensors For example it is assumed that the resident is located at point 1 in the figure when only sensor a signals ON while the resident is located at point 2 when sensors a and b both output ON signals The location accuracy of this system can be defined the maximum distance between the estimated points and the resident For example when a resident enters sensing area A the resident is assumed to be at point 1 On the assumption that a resident can be represented by a 6 point and the radius of the sensing area of a PIR sensor is 1 m we know that the location accuracy is 1 m because the maximum error occurs when the resident is on the boundary of sensing area A Alternatively when the resident is in sensing area B the resident is assumed to be at point 2 and the maximum location error occurs when the resident is actually at point 3 In this case the error is 3 2 m which is the distance between points 2 and 3 Therefore the location accuracy of the total system shown in Fig 3 can be regarded as 1 m which is the maximum value of the location accuracy of each area Since the number of sensors and the size of their sensing areas determine the location accuracy of the PILAS it is necessary to arrange the PIR sensors properly to guarantee the specified system accuracy Fig 3 The location recognition algorithm for PIR sensors In order to determine the resident s location precisely and increase the accuracy of the system it is desirable to have more sensing areas with given number of sensors and to have sensing areas of similar size Fig 4 shows some examples of sensor arrangements and sensing areas Fig 4 a and 4 b show the arrangements with nine sensors that produce 40 and 21 sensing areas respectively The arrangement in Fig 4 a is better than Fig 4 b in terms if the number of sensing areas However the arrangement in Fig 4 a has some areas where a resident can not be detected and lower location accuracy than that in Fig 4 b Fig 4 c shows an arrangement with twelve sensors that five 28 sensing areas without any blind spots 7 Fig 4 Location accuracy according to the sensor arrangement of PIR sensors a 40 sensing areas b 21 sensing areas c 28 sensing areas with twelve sensors When PIR sensors are installed around the edge of a room as shown in Fig 4 c it sometimes may give awkward results One example is shown in Fig 5 Fig 5 a shows the path of a resident If we mark the estimated points by using the sensor location or the midpoint of adjacent sensors it will be a zigzagging patterns as shown in Fig 5 b In order to alleviate this we may regard the sensors on the edges to be located a little inwards which give the result shown in Fig 5 c 8 Fig 5 The effect of compensating for the center point of the outer sensors a Resident s movement b Before compensating for the outer sensors c After compensating for the outer sensors III PERFORMANCE EVALUATION OF THE PILAS A Resident detection method using PIR sensors Since the PILAS recognizes the resident s location by combining outputs from all the sensors belonging to one cell determining whether a single sensor is ON or OFF directly influences location accuracy In general because the ON OFF values can be determined by comparing a predefined threshold and the digitized sensor output acquired by sampling the analog signal from a PIR sensor it is necessary to choose an appropriate signal level for the threshold For example Smart Floor which is another non terminal method can recognize a resident s location exactly by comparing the appropriate threshold and a sensor value because a pressure sensor outputs a constant voltage based on the resident s weight when he remains at a specific point However because a PIR sensor measures the variation in the infrared signal produced by a moving human body its output is in analog form as shown in Fig 6 That is as the variation in the infrared radiation from a resident increases when a resident enters a sensing area the PIR sensor outputs 9 an increasing voltage Conversely the voltage decreases as the resident leave the sensing area If the resident does not move within the sensing area the variation in the infrared radiation does not exist and the PIR sensor outputs zero voltage Therefore it is very difficult to deter mine when a resident is staying resident within a specific sensing area using only the voltage or current threshold of a PIR sensor Fig 6 Signal output of PIR sensor In order to guarantee the location accuracy of the system the resident detection method must meet several requirements First if no resident is present within a sensing area the PIR sensor should not output ON signal That is the PIR sensor must not malfunction by other disturbances such as a moving pet temperature change and sunlight Second it should be possible to precisely determine the point in time when a resident enters and leaves a sensing area That is in spite of variations in sensor characteristics resident s speed and height it should be possible to determine the time point exactly Finally because the output voltage of a PIR sensor does not exceed the threshold voltage when the resident does not move within a sensing area it is necessary to know if a resident stays within the sensing area In order to satisfy these requirements this paper introduces the following implementation method for the resident detection method for PIR sensors First in order to eliminate PIR sensor malfunctioning due to pets or temperature changes a Fresnel lens which allows human infrared waveforms to pass through it while rejecting other waveforms is installed in front of the PIR sensors Second when the output of a PIR sensor exceeds the positive threshold voltage and this state is maintained for several predefined sampling intervals that the resident has entered a sensing area Here the threshold must be sufficient for the method to distinguish variation in the resident s infrared from an environmental infrared signal caused by pets or temperature change Moreover when the sensor s output falls below a negative threshold voltage and this status is maintained for several sampling intervals it is assumed that the resident has left the sensing area Finally when the output voltage remains between the two threshold voltages for example when the resident is not moving inside the sensing area the output of the corresponding PIR sensor is changed from ON to OFF At this time if other sensors installed near this sensor do not output ON signal the method regards the resident as remaining within the corresponding 10 sensing area B Performance evaluation using an experimental test bed In order to verify the feasibility of the PILAS an experimental test bed was implemented Since the intelligent location based service in the smart home does not require very high location accuracy we designed the system to have a location accuracy of 0 5 m Figure 7 shows the experimental test bed in a room measuring 4 4 2 5 m width length height In the experiment twelve PIR sensors were fixed on the ceiling using the arrangement shown in Fig 4 c An Atmel AT89C51CC001 microcontroller 17 was used for signal processing and judging ON OFF and a Nippon Ceramic RE431B PIR sensor 18 and NL 11 Fresnel lens were used Especially a horn was installed on each PIR sensor to limit the sensing area to the circle with 2 m diameter Fig 8 shows the experimental results with the horn In the figure the RE431B sensor outputs the signal shown in a when a resident passes through the sensing circle while it outputs the irregular sig