Improved active beacon system using multi-modulation of ultrasonic sensors for indoor localization

Several kinds of indoor localization systems have been developed for estimating object's position lately. They are classified according to the environment, the purpose of application, the media type and so on. In this paper, we propose an improved active beacon system, having the ultrasonic media type, which can be used for indoor localization; moreover, it utilizes pan-tilt mechanism for targeting the object. But it has a low sampling rate because the pan-tilt mechanism is operating and its processor is scheduling. What is more, it includes shortcoming such as limited arrival-distance of ultrasonic signal and its high sensitivity to noises. In order to overcome these problems, we applied the multi-modulation of ultrasonic sensors - using two ultrasonic sensors with different frequencies - to improve the sampling rate of this system. In addition, such problems mentioned above were ameliorated using a more sophisticated micro-processor like 'DSP' and a signal detection board developed in KIST; consequently, the positioning accuracy of this system has been increased highly through the redesigned system.