Patent ID: 7306053

Claim:
In a system for tracking a boring tool which is moved in an underground region using a drill string having a length that extends to the boring tool and said boring tool having an overall orientation that is characterized by a pitch orientation, a yaw orientation and a roll orientation and which is steerable underground in the region using said roll orientation, a method comprising: advancing the boring tool over a path segment from a known, start position to an end position, where the path segment forms a portion of an overall drill path that is taken by the boring tool and includes a segment length; measuring a series of incremental roll positions during advancement over the path segment; establishing an incremental change in the pitch orientation and an incremental change in the yaw orientation of the boring tool for the path segment based, at least in part, on the series of incremental roll positions for use in tracking the boring tool; and extrapolating from said start position of the current path segment to determine a predicted location of the end position based, at least in part, on the start position, the incremental change in the pitch orientation and the incremental change in the yaw orientation.