Automatic alignment system for earth boring rig

An alignment system for a movable vertical structure having power movement systems thereon, said alignment system adapted to maintain said structure in a substantially exact vertical orientation with respect to the center of gravity of the earth, and comprising:

• first lateral sensing means on the vertical structure, located in one plane of movement of said structure and arranged to sense the direction of movement of the structure vertical axis in a direction parallel to said one plane;
• second lateral sensing means on the vertical structure, located in a second plane at substantially right angle orientation to said first plane of movement of the structure, said second sensing means arranged to sense the direction of movement of the structure vertical axis in a direction parallel to said second plane;
• signal means operatively connected to said first and second sensing means and adapted to generate signals in response to activation of said sensing means, said signal means operatively connected to the power movement systems on the vertical structure;
• and
• wherein at least one of said first and second sensing means comprises strain gauge means attached at one end to movable means mounted on the vertical structure, said strain gauge means adapted to generate electrical signals in response to movement of said movable means on the vertical structure.