Patent ID: 8122974

Claim:
In a drilling machine for drilling a series of holes where the drilling machine comprises: a carrier vehicle movable over the terrain, a boom mounted on the vehicle for movement side to side on the vehicle, a mast for supporting a drilling tool where the mast is carried on an outer end of the boom and movable about two separate axes relative to the end of the boom, the improvement of an apparatus for controlling the drilling machine comprising: a sensor assembly; the sensor assembly including a first sensor responsive to the earth's magnetic north direction to provide an output indicative of an azimuth angle between Magnetic North and an orientation of the sensor assembly; the sensor assembly including two second sensors each providing an output indicative of an inclination angle of the sensor assembly with respect to a respective one of two vertical planes arranged at an angle to one another, where the vertical planes are perpendicular to the earth's surface; the sensor assembly being mounted on the mast; and a controller responsive to the outputs of the first sensor and the two second sensors arranged to determine a set of angles, including a target azimuth angle and two target inclination angles, for the mast for drilling each holes of the series of holes; where the set of angles including the target azimuth angle and two target inclination angles are determined after the carrier vehicle is moved.