Ultrasonic Sensor Based Smart Fan

Nowadays in the era of Intelligent Systems; a smart fan is very much essential to the concept of "Smart Homes".Thus taking in view of the recent developments in home automation we developed a circuit which tracks the presence of person in a room.Most of the previous researches included IR and PIR sensors as the tracking sensor.Performance of Infrared sensors has traditionally been limited by their poor tolerance to light reflections such as ambient light or bright object colors.The Passive Infrared sensors have tolerance problems with temperature limit values.But ultrasonic distance sensors do not have gaps in the coverage zone like a PIR sensor and overall detection range is comparable to that of a PIR sensor.Thus in this paper we suggested the use of ultrasonic sensor module to measure the distance between the human and based on the pre-defined setpoints we have varied the speed of a small fan in the prototype .AT89s51 microcontroller and the ultrasonic transducer module HC-SR04 forms the basis of this circuit.The ultrasonic module sends a signal to the object, then picks up its echo and outputs a wave form whose time period is proportional to the distance.The microcontroller accepts this signal, performs necessary processing and varies the intensity of the fan.We also depicted a concept where these sensors can be attached to overhead ceiling fans propose use of Maximum length sequence (MLS) diffusors for sensing a 360 degree circumference beneath the fan and a thermostat to maintain the temperature in the room.