Automatic blade angle controller system

An automatic blade level controller system utilizing the gravitational force vector comprising:

• a. a support member;
• b. a controlled member pivotally attached to said support member;
• c. an opaque enclosure rigidly affixed to said controlled member, said opaque enclosure having a level reference position, thereby establishing a reference position for said controlled member depending upon the placement of said opaque enclosure with respect to said controlled member,
• d. a closed, transparent manometer partially filled with an opaque liquid located inside said enclosure, said liquid forming two surfaces inside said manometer;
• e. a pair of opaque floats floating respectively on the two surfaces of said liquid in said manometer each said float being shaped such that in combination with the liquid surface cohesive or tension effects each said float is centered in said manometer without touching the manometer wall thereby eliminating columb friction forces and providing linear viscous forces from couette flow between each said float and its respective manometer wall whereby undesirable hysteresis effects are eliminated, said floats having flat top surfaces.
• f. a light source located inside the perimeter of said manometer;
• g. a first and a second light detecting means located on opposite sides of said light source, light from said light source passing through said manometer in order to strike said first and second light detecting means, light from said light source being partially blocked from impinging upon said first and second light detecting means by said surfaces of said floats on each side of said manometer, each said first and second light detecting means outputting a direct current voltage level proportional to the amount of light impinging, thereon, each said light detecting means receiving an equal amount of light from said light source when said level sensing means is in said level reference position;
• and
• h. an error signal being generated by voltage differences when each said light detecting means receives different amounts of light from said light source, and
• i. means connected between said support member and said controlled member and receiving said error signal for returning said controlled member to its reference position.