Kensuke Sawada

Hybrid positioning system combining spatially continuous and discrete information for indoor location-based service

Positioning systems have gained importance in situations where various location-based services have been installed. Although the combination of Wi-Fi positioning with inertial navigation is considered to be accurate for indoor use, it is important to avoid increasing the error when using estimated positions for location-based services. In this paper, we propose a positioning system that combines several positioning methods with different characters to avoid increasing the error. Demonstration experiments that show the effectiveness of the proposed system in an exhibition hall are also described.

Advanced car positioning method using infrared beacon

We developed a novel vehicle positioning method using the existing infrared beacon infrastructure that has been spreading on Japanese roadways. This method can realize measurement accuracy of 50 cm whenever the vehicle passes under an infrared beacon roadside unit. GPS is now a popular means of providing vehicle-positioning systems. When applying GPS to more critical purposes, however, it generally lacks the necessary accuracy and reliability. To solve these problems, we have proposed a new vehicle positioning method using the existing infrared beacon infrastructure. This method is based on the principle of precisely locating optical source of the infrared-rays being received. Moreover, the infrared beacon infrastructure is designed for short-range communication, and thus offers high reliability. It is also easier to estimate the direction of the source of infrared-rays than radio waves since infrared-rays travel in a straight line. Many advanced ITS services and solutions are expected by utilizing this method.

User-installable Indoor Positioning System Using a Wi-Fi Beacon and PDR Module

This paper describes a user-installable indoor positioning system based on a new wireless beaconing method called a Wi-Fi location beacon, and a pedestrian dead reckoning (PDR) module. In the proposed system, the new wireless beaconing method offers an accurate positioning system using a high-gain beam antenna in the 5 GHz Wi-Fi band. The antenna forms a narrow hotspot of received signal strength (RSSI) in the space immediately below itself; the user devices detect the hotspot by monitoring the RSSI. The beaconing module is also resistant to jamming by other wireless systems and noise. Experimental results show that the proposed system can work in a high density Wi-Fi environment with over 100 Wi-Fi stations, and the positioning error of the proposed system at CDF = 90% is about 3.5 m. The positioning accuracy of the proposed system is slightly inferior to previous systems based on the Wi-Fi fingerprint method, but it achieves a similar function using a user-installable system which is easier to install and maintain than previous systems.