AGV position P(x,y) is given by the equations [Premi and Besant, 1983]
An absolute or indexed incremental position encoder that
monitors laser scan azimuth is used to establish platform heading. This
technique has some inherent advantages over the use of passive retroreflective
targets, in that false acquisition of reflective surfaces is eliminated,
and longer ranges are possible since target reflectivity is no longer a
factor. More robust performance is achieved through elimination of target
dependencies, allowing a more rapid scan rate to facilitate faster positional
updates. The one-way nature of the optical signal significantly reduces
the size, weight, and cost of the onboard scanner with respect to that
required for retroreflective beacon acquisition. Tradeoffs, however, include
the increased cost associated with installation of power and communications
lines and the need for significantly more expensive beacons. This can be
a serious drawback in very-large-area installations, or scenarios where
multiple beacons must be incorporated to overcome line-of-sight limitations.