Horizontal directional drilling machine employing inertial navigation control system and method

A system for controlling an excavation implement for use in horizontal directional drilling, comprising:

• a cutting tool coupled to a drill pipe;
• a driving apparatus coupled to the drill pipe for driving the cutting tool along a generally horizontal underground path, the driving apparatus comprising at least one pipe sensor that senses movement of the drill pipe;
• a navigation sensor unit provided proximate the cutting tool, the navigation sensor unit comprising a plurality of navigation sensors, each of the navigation sensors sensing movement of the cutting tool in a manner differing from that of other navigation sensors of the plurality of navigation sensors;
• and
• a controller communicatively coupled to the driving apparatus and the navigation sensor unit, the controller monitoring each of the navigation sensors and the pipe sensor, determining a particular navigation sensor having an acceptable accuracy, and using sensor data received from at least the particular navigation sensor to control cutting tool movement along the underground path.

A system for controlling an excavation implement for use in horizontal directional drilling, comprising:

• a cutting tool coupled to a drill pipe;
• a driving apparatus coupled to the drill pipe for driving the cutting tool along a generally horizontal underground path, the driving apparatus comprising at least one pipe sensor that senses movement of the drill pipe;
• a navigation sensor unit provided proximate the cutting tool, the navigation sensor unit comprising a plurality of navigation sensors, each of the navigation sensors producing sensor data by sensing movement of the cutting tool in a manner differing from that of other navigation sensors of the plurality of navigation sensors;
• and
• a controller communicatively coupled to the driving apparatus and the navigation sensor unit, the controller monitoring each of the navigation sensors and applying a weighting algorithm to sensor data received from the navigation sensors when computing a location or an orientation of the cutting tool, the weighting algorithm applied by the controller accounting for changes in navigation sensor performance as the cutting tool moves along the underground path.