Method and apparatus for sensing and measuring relative position and

Abstract

Apparatus for measuring relative movement between two points which represents relative movement between two items or between two parts of the same item includes a radiation source such as a light source which generates three orthogonal light beams appearing to originate at a common point, said common point constituting one of the two points, and the light source being secured to one of the items or parts of an item. A radiation sensor capable of detecting in three two-dimensional sensing planes the position of each of the three orthogonal radiation beams, such as three light sensing arrays arranged in three orthogonal planes, each of the three orthogonal sensing planes intersecting at an origin point which constitutes the other of the two points is secured to the other item or part of an item. A calculation unit such as a microprocessor is provided for calculating the relative position of the two points at any particular time from the determined positions of the three radiation beams striking the sensing means at that time and may also be programmed to relate the relative position of the two points and changes in such relative position to the relative position and changes of the two items or parts of an item to which the radiation source and sensor are secured. The movement between the two points, the two items, or parts of the same time is determined by calculating the difference in positions between two measured relative positions.