System for tracking and/or guiding an underground boring tool

A method of tracking the position of a boring tool in the ground as the latter moves along a path which lies within a coordinate system, said method comprising the steps of:

• (a) providing the boring tool with a pitch sensor and means for transmitting an electromagnetic field and moving said boring tool along a path;
• (b) providing two detectors, each of which has an electromagnetic field receiving antenna assembly including first, second and third receiving antennas mounted orthogonal to one another, positioning said detectors at two separate fixed locations within said coordinate system, and determining the positions and orientations of the first, second and third antennas of each detector within said coordinate system;
• (c) at least periodically transmitting said electromagnetic field from said boring tool at various points along the path of movement of said boring tool;
• (d) when the boring tool moves a distance along said path from the one point thereof to a second point, taking measurements of first, second and third components of the intensity of said electromagnetic field using the three antennas of each said detector;
• and
• (f) from the electromagnetic field intensity taken when the boring tool is at said second point, determining at least to an approximation the coordinates of the boring tool and its yaw angle at said second point within the coordinate system.

In a system in which a boring tool is moved through the ground in a region, an arrangement for tracking the position and/or guiding the boring tool as it moves through the ground, said arrangement comprising:

• (a) moans located within said boring tool for transmitting an electromagnetic field
• (b) one or more detector means for receiving said electromagnetic field, each detector means having an electromagnetic field receiving antenna assembly including at least one antenna for measuring at least one component of the intensity of said electromagnetic field, each detector being positioned at a fixed position with its antenna at a particular orientation within said region;
• c) means for determining certain initial conditions prior to drilling which include the positions of said detectors in said region, the particular orientation of the antenna associated with each detector provided and an initial position and orientation of the boring tool;
• and
• (d) processing means for using at least one measured component of the intensity of said electromagnetic field, which is obtained using said detector or detectors after the boring tool moves a distance along said path, in determining, at least to an approximation, the position of the boring tool after moving said distance.

In a method of tracking the position and certain orientation parameters of a boring tool in the ground as the latter moves along a path from a first point to a second point within a particular coordinate system, the boring tool being provided with means for transmitting an electromagnetic field, the improvement comprising the steps of:

• (a) providing a plurality of detectors, each having an electromagnetic field receiving antenna assembly;
• (b) positioning each detector provided at a fixed position and at a particular orientation within said coordinate system but not along the intended path of movement of said boring tool and determining said fixed position and particular orientation;
• and
• (c) using said detectors at least in part to determine the position and orientation of said boring tool when the latter is at said second point.