Dlight: Indoor Device-free Passive Tracking Using Light Sensor Networks

As a new platform to get information, sensor networks can monitor and collect a variety ofinformation that come form the monitored target. Sensor networks can improve the ability thatthe people connect with the computers remotely. This technology can be widely applied in theareas of military usage, disaster protection, environmental monitoring, intelligent householdappliances, intelligent traffics and anti-terrorism attack. Within the technology of sensornetworks, localization technology can not only make sure the position of the sensor networknodes, but also is the basis of the tracking technology.With respect to tracking problems, there are two main directions. One direction assumesthat a target being tracked with some assistant advices (e.g. wireless sensor node, PDAs) suchthat the target can be easily detected by other anchor sensor nodes. This is called device-basedtracking. In contrast, the other direction assumes that the target being tracked is device-free, i.e.,the target carries no any assistant device and the tracking procedure is considered to be“passive”.In this thesis, we study the passive (device-free) tracking problem using sensor networks. Atfirst, this thesis introduces the background of the tracking system using sensor networks, ithighlights a tracking system which use light sensor networks system-iLight. Then it proposes anoval tracking system, Dlight, which uses light sensor networks and ordinary light source. Thesystem is arranged in the environment which has only one light source, just like ordinary homelight source. It can track the target’s walking trajectory by the Dlight system. When the targetwalks through the room, the light sensor will generate different reactions. This thesis discussestwo different light sources: circular lamp source and fluorescent lamp source. For each source,the Dlight system utilizes a suitable way to get the target’s walking trajectory, and then inducestheir relationships and the differences.To verify the feasibility and superiority of the Dlight tracking system, a series ofexperiments are performed in the environment with the two different light sources-circular lampand fluorescent lamp. After the experiments, it concludes accuracy of the Dlight tracking system,and also it gets knowledge of the facts that affect the degrees of accuracy. At last, it compares thedifference between the iLight tracking system and the Dlight tracking system from differentaspects, and then it points out the advantages and disadvantages of the two different tracking systems.