Straight line mechanism

An apparatus for maintaining motion of a platform in a straight line comprising:

• a) static base;
• b) a platform;
• c) a first arm assembly having first terminal portion pivotally connected at a first pivot point to a first portion of said static base and a second terminal portion pivotally connected to said platform at a second pivot point, said first arm assembly being so constructed to permit changes in the distance between said first and second pivot points, but concomitantly being constrained to movement in a desired first plane;
• and
• d) a second arm assembly having a respective first terminal portion pivotally connected at a third pivot point to a second portion of said static base and a respective second terminal portion pivotally connected to said platform at a fourth point, said second arm assembly being so constructed to permit changes in the distance between said third and fourth pivot points, but concomitantly being constrained to movement in a desired second plane, which is angularly disposed from said first plane, the motion of said platform being constrained to a straight line when the distance between said first and second pivot points and/or the distance between said third and fourth pivot points is changed, said straight line having a direction parallel to an imaginary line defined by the intersection of said first and second planes,
• said static base including straight line direction rotary actuation means attached to both arm assemblies for providing adjustments in the angular orientation of the plane of said arm assembly, thereby providing adjustments in the direction of said straight line.