Compensated magnetic sensor for use on highly magnetized vehicles

Apparatus for sensing the direction of the horizontal component of the earth's magnetic field to implement navigating a vehicle along a desired course, comprising:

• a baseplate secured to a normally horizontal surface of the vehicle;
• a pedestal mounted to the baseplate;
• a torroidal magnetic sensor mounted to the pedestal and having a centrally disposed hole extending therethrough;
• a post mounted to the pedestal and passing through the centrally disposed hole and drawn to a point on its end opposite the mounted end;
• a hollow cylindrical core having a closed end and carrying a winding of insulated wire to provide a coil which surrounds the magnetic sensor, and carrying a detent on the inside of the closed end which pivotally engages the pointed end of the post;
• a hollow cylindrical case having a closed end and mounted to the baseplate to surround the coil;
• a screw axially aligned with the pose and in threaded engagement with the closed end of the case, and adjusted in the case to be just clear of a protrusion on the outside of the closed end of the core and axially aligned with the detent so that the coil is pendulously-supported between the pointed end of the post and the screw for displacement about pitch, roll and yaw axes of the vehicle;
• the case being partially filled with a fluid to damp out extreme displacements about said axes;
• and
• the coil being energized to generate a magnetic field which opposes the earth's vertical field to essentially eliminate the effect of said field on the sensor when the vehicle pitches and rolls, with the magnetic effects induced from the vehicle axes to the sensor axes when the vehicle pitches and rolls being essentially eliminated by virtue of the sensor being mounted to the vehicle surface.