Kyushu University Academic Staff Educational and Research Activities Database
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Hiroaki Togashi Last modified date:2018.05.14

Graduate School
Undergraduate School

Academic Degree
Country of degree conferring institution (Overseas)
Field of Specialization
Activity recognition, Localization, Intelligent Transportation System
Total Priod of education and research career in the foreign country
Outline Activities
Researches on localization system and sensing system utilizing wireless backhaul network
Research Interests
  • Researches on localization system and sensing system utilizing wireless backhaul network
    keyword : Sensing system, localization, wireless backhaul
Academic Activities
1. GPS (Global Positioning System) is widely used to estimate positon of objects. However, it cannot accurately estimate which road the vehicle is running such as grade separated crossing, and it cannot estimate vehicular position in tunnel. This paper presents a new position estimation algorithm for moving vehicles based on RFIDs (Radio Frequency IDentifications) placed on roadsides and lane boundaries, and multiple on-car RFID receiver antennas, aiming to overcome these problems. This algorithm employs two novel ideas: (1) compute pair-wise positions of on-car antennas using the RSSI (Received Signal Strength Indication) of all pairs of received RFID signals, and (2) use a dynamic weighting function to assign higher weights to the positions estimated based on RFIDs closer to the receiver antennas. The results obtained from our field experiments indicate that the proposed method achieved 0.7-meter localization accuracy for the position estimation when RFIDs were placed at 0.5-meter intervals and a vehicle has 8-antennas. Analysis of localization accuracy in road-width direction revealed that the proposed method allows a moving vehicle to recognize which lane it is in. This result also indicates that the proposed method reduced error in estimating position to 31-70%, compared to existing methods. .
1. Hiroaki Togashi, Wireless Backhaul-based Sensor Network and its Applications, 2017.03, In order to set up wireless sensor network,a significant number of wireless access points must be installed.
However, its installation cost tends to be expensive, because all access points must be wired to the core network e.g., the internet, in
existing wireless sensor networks.
Wireless backhaul is a wireless multi-hop network in which access points are linked wirelessly with the capability of relaying packets.
This technology enables to achieve a wide Wi-Fi coverage area without installing a huge amount on access cable, and it is very suitable for
setting up a wireless sensor network.
This presentation introduces wireless sensor network based on wireless backhaul technology, and applications work on this network
infrastructure. For example, we proposed "Criminal Fishing system" identifies the media access control (MAC) address of a culprit’s device from probe request signals captured by access points during the period in which a culprit remains near the incident scene.
We also proposed a pedestrian tracking system that uses Wi-Fi beacons held by target persons and Wi-Fi access points placed widely and
densely in a specified area. Target users’ positions are estimated on the basis of probe request signals broad-cast by the Wi-Fi beacons..
2. Hiroaki Togashi, Yuki Yamaguchi, Ryuta Abe, Junpei Shimamura, Hiroshi Furukawa, Network-based positioning and pedestrian flow measurement system utilizing densely placed wireless access points, SEVENTH INTERNATIONAL CONFERENCE ON INDOOR POSITIONING AND INDOOR NAVIGATION (IPIN 2016), 2016.11, Although accurate positioning systems are important to provide location-aware services, solutions that are applicable in high-rise areas and inside buildings have not yet been realized. We propose an accurate positioning system that utilizes widely and densely placed Wi-Fi access points. The proposed system utilizes probe request signals broadcast by mobile devices to estimate their positions. The positioning algorithm is based on proximity detection using received signal strength indication. In addition, the proposed method employs a computation time reduction strategy and error reduction techniques. The proposed system can also show pedestrian flow, which is valuable information for developing shop branching plans, street improvement, and so on. The experimental results show that the proposed positioning system achieved an accuracy of 5.36 m. The system can also visualize pedestrian flow trends in a given Wi-Fi coverage area based on the position estimates..
3. Hiroaki Togashi, Yasuaki Koga, Hiroshi Furukawa, "Criminal Fishing System Based on Wireless Local Area Network Access Points", 2016 IEEE International Conference on Multisensor Fusion and Integration for Intelligent Systems, 2016.09, This paper describes a system for criminal
identification that utilizes a large number of wireless local area
network (LAN) access points and cameras. The proposed
“Criminal Fishing system” identifies the media access control
(MAC) address of a culprit’s device from probe request signals
captured by access points during the period in which a culprit
remains near the incident scene. Experimental results
demonstrate that the proposed system could identify the culprit
MAC address 10 out of 10 times in an indoor experiment and 8
out of 8 times in an outdoor experiment, in case that the culprit’s
radio wave fingerprint could be captured..
Membership in Academic Society
  • Information processing Society of Japan
Educational Activities
Student Assitant of "Modeling Simulation" in Keio University, Faculty of Environmental Infotmation (Fall Semester, 2004)