Towards particle filter SLAM with three dimensional evidence grids in a flooded subterranean environment

This paper describes the application of a RaoBlackwellized Particle Filter to the problem of simultaneous localization and mapping onboard a hovering autonomous underwater vehicle. This vehicle, called DEPTHX, equipped with a large array of pencil-beam sonars for mapping, and autonomously explore a system of flooded tunnels associated with the Zacaton sinkhole in Tamaulipas, Mexico. Due to the three-dimensional nature of the tunnels, we describe an extension of traditional two dimensional evidence grids to three dimensions. In May 2005, we collected a sonar data set in Zacaton. We present successful SLAM results using both the real-world data and simulated data