Indoor Positioning and Navigation Using Time-Of-Flight Cameras

Abstract

The development of indoor positioning techniques is booming. There is a significant demand for systems that have the capability to determine the 3D location of objects in indoor environments for automation, warehousing and logistics. Tracking of people in indoor environments has become vital during firefighting operations, in hospitals and in homes for vulnerable people and particularly for vision impaired or elderly people [1]. Along with the implementation of innovative methods to increase the capabilities in indoor positioning, the number of application areas is growing significantly. The search for alternative indoor positioning methods is driven by the poor performance of Global Navigation Satellite Systems (GNSS) within buildings. Geodetic methods such as total stations or rotational lasers can reach millimeter level of accuracy, but are not economical for most applications. In recent years, network based methods which obtain range or time of flight measurements between network nodes have become a significant alternative for applications at decimeter level accuracy. The measured distances can be used to determine the 3D position of a device by spatial resection or multilateration. Wireless devices enjoy widespread use in numerous diverse applications including sensor networks, which can consist of countless embedded devices, equipped with sensing capabilities, deployed in all environments and organizing themselves in an ad-hoc fashion [2]. However, knowing the correct positions of network nodes and their deployment is an essential precondition. There are a large number of alternative positioning technologies (Fig. 1) that cannot be detailed within the scope of this paper. An exhaustive overview of current indoor position technology is given in [3]. Further focus will be on optical methods.