Apparatus and method for maintaining control of a drilling machine

A system for controlling a drilling machine adapted to drivingly engage a drill string having a downhole tool, the drilling machine producing an output having a plurality of kinematic components, with each such output component responsive to a corresponding component input signal, comprising:

• a dynamic control system adapted to regulate each component input signal in response to dynamic user input;
• a component maintenance system adapted to automatically maintain at least one component input signal at a user-selected component maintenance level in response to a component maintenance signal;
• and
• a component interrupt system adapted to discontinue automatic maintenance of said component input signal in response to a component interrupt signal.

A system for controlling a drilling machine having a pipe handling assembly for adding and removing a plurality of pipe sections from a drill string, the machine producing a thrust output in response to a thrust input signal and a rotation output in response to a rotation input signal, comprising:

• a dynamic control system adapted to regulate the thrust input signal and the rotation input signal in response to dynamic user input;
• a maintenance system adapted to automatically maintain at least one of the rotation input signal and the thrust input signal at a user-selected maintenance level for the same input signal in response to a maintenance signal;
• and
• an interrupt system adapted to discontinue automatic maintenance of said at least one of the rotation input signal and the thrust input signal at the maintenance level for the same input signal in response to an interrupt signal.

A method for controlling a horizontal drilling machine having a drill string with a downhole tool which produces a thrust output in response to a thrust input signal and a rotation output in response to a rotation input signal, the method comprising:

• selecting a subsurface bore path along which the downhole is to moved;
• axially advancing the drill string so as to move the downhole tool along at least a portion of the selected subsurface bore path;
• regulating the thrust input signal and the rotation input signal in response to a dynamic user input;
• automatically maintaining the thrust input signal at a user-selected thrust maintenance level in response to a thrust maintenance signal;
• automatically maintaining the rotation input signal at a user-selected rotation maintenance level in response to a rotation maintenance signal;
• discontinuing automatic maintenance of thrust input signal at the thrust maintenance level in response to a thrust interrupt signal;
• and
• discontinuing automatic maintenance of rotation input signal at the rotation maintenance level in response to a rotation interrupt signal.