Apparatus and method for measuring rotation angle

A method for measuring the relative change in position of an object in two or three dimensions including angle of rotation as said object is moved between a first, home position and a second, relatively rotated position utilizing a floating rotary support, a two-point cursor and a digitizer tablet, comprising the steps of:

• positioning said object on said floating rotary support in a home position with said rotation axis of said object aligned with one point of said two point cursor;
• rotating said object to said second, relatively rotated position;
• determining X and Y coordinates for two points at said second, relatively rotated position of said object utilizing said two point cursor and said digitizer tablet;
• and
• calculating said rotation angle from said X and Y coordinate of said two points.

An apparatus for measuring the relative change in position of an a wheel of a vehicle in two or three dimensions including angle of rotation as said wheel is rotated about a rotation axis, comprising:

• a frame;
• a floating rotary support for the wheel for which rotation angle is to be measured, said support being mounted to said frame and allowing free lateral movement of said support relative to said frame in X and Y coordinate directions;
• means for centering the rotation axis of said wheel on said floating rotary support, said centering means including a pair of cooperating, upstanding guides mounted to said rotary support and defining a space therebetween to just receive said wheel so as to provide side-to-side alignment and a depression formed in said support to receive said wheel so as to provide fore-and-aft alignment;
• a cooperating cursor and digitizer tablet to identify X and Y coordinates of at least said second, relatively rotated position of said wheel, one of said cursor and digitizer tablet being fixed to said rotary support for movement therewith, the other of said cursor and digitizer tablet remaining stationary;
• and
• means for calculating the rotation angle of said wheel from the X and Y coordinates of said second, relatively rotated position.

An apparatus for measuring the relative change in position of an object in two or three dimensions including angle of rotation as said object is moved between a first, home position and a second, relatively rotated position, comprising:

• a two-point cursor having a known, fixed linear distance separating said first point and said second point;
• a digitizer tablet cooperating with said two-point cursor to identify X and Y coordinates of at least said second, relatively rotated position of said object;
• one of said two-point cursor and digitizer tablet being operatively connected to said object for movement therewith, the other of said two-point cursor and digitizer tablet remaining relatively stationary;
• and
• means for calculating the rotation angle of said object from at least the X and Y coordinates of both points of said cursor in said second, relatively rotated position.

A method for measuring the relative change in position of an object as that object is moved between a first, home position and a second, relatively rotated position utilizing a two-point cursor and cooperating digitizer table, comprising the steps of:

• operatively connecting one of said two-point cursor and digitizer tablet to said object for movement therewith;
• maintaining the other of said two-point cursor and digitizer tablet relatively stationary;
• determining the X and Y coordinates of said first, home position for both points of said two-point cursor;
• rotating said object to said second relatively rotated position;
• determining the X and Y coordinates of said second, relatively rotated position for both points of said two-point cursor;
• calculating said rotation angle from said X and Y coordinates of both points of said two point cursor in at least said second, relatively rotated position.