Technical Report CIS9808

Title: Fusion Fixation and Odometry for Vehicle Navigation
Authors: Amit Adam and Ehud Rivlin
Abstract: To be able to operate appropriately, an autonomous guided vehicle (AGV) must keep a sufficiently accurate track of its location and orientation with respect to some given coordinate system. This paper deals with the problem of determining the position and orientation of an AGV by fusing information from odometry with information coming from the vision system. In particular, the possibility of pointing a camera in different directions is used to fixate on a point of the environment while the AGV is moving. We show that by fixating on a landmark one can improve the navigation accuracy even if the scene coordinates of the landmark are unknown. This is a major improvement over previous methods which assume that the coordinates of the landmark are known. In particular, using this approach any point of the observed scene can be selected as a landmark, and not just pre-measured points. Next we assume we have an initial estimate of the coordinates of the fixation point. We show that in this case the fusion process needs only very simple measurements from the vision system - namely the pan and tilt angles from the vehicle to the point. We formulate the fusion process of these measurements with odometry information. We also suggest an "emergency procedure" for obtaining absolute position once the vehicle gets lost. Thus, we show that fixation is basically a simpler procedure than previously mentioned methods. The simplification comes from the fact that only one point needs to be tracked as opposed to multiple points in other methods. This disposes of the need to be able to identify which of the landmarks is currently being tracked, through a matching algorithm or by other means. We support our findings with both experimental and simulation results.
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