Directional drilling device and method for calibrating same

A directional drilling device, comprising:

• a housing;
• a drive shaft extending through the housing, wherein a drill bit is coupled to an end of the drive shaft;
• a plurality of magnetic field sensors positioned in the housing and in signal communication with a control device also positioned in the housing, wherein the magnetic field sensors are configured to determine a magnetic interference declination influenced by a magnetic interference field as a magnetic interference flux density and to transmit a magnetic interference declination value corresponding to the magnetic interference flux density to the control device, and wherein the magnetic field sensors are calibrated by homogenous magnetic field generated by a Helmholtz coil;
• and
• a directional control device coupled to the housing and controllable by the control device to control a position of the directional drilling device;
• wherein the control device is configured to generate a correction value based on the magnetic interference declination value.

A method for operating a directional drilling device, comprising:

• (a) determining a magnetic interference declination influenced by a magnetic interference field as a magnetic interference flux density;
• (b) determining a magnetic interference declination value corresponding to the magnetic interference flux density;
• (c) generating a correction value based on the magnetic interference declination value, wherein the correction value corresponds to a deviation of the magnetic interference flux density from a reference magnetic flux density measured at a reference standard;
• and
• (d) controlling a direction of the directional drilling device based on the correction value.