Abstract: A three dimensional graphics tablet for determining the three dimensional coordinates of points on an object placed on a supporting plane. The apparatus includes an articulated arm having at least two link elements connecting a contacting tip element to the support for rotational movement about a plurality of mutually angulated axes. By means of the arm articulation, the contacting tip element can be moved to arbitrary locations within a defined volume. Potentiometers are provided for measuring each of the angles of rotation about the mutually angulated axes. These potentiometers generate signals which collectively determine the coordinates of the location of the tip element. Embodiments are disclosed having three and four degrees of freedom and a portable embodiment including a clamp or bracket are disclosed.

Abstract: A three dimensional graphics tablet for determining the three dimensional coordinates of points on an object placed on a supporting plane. The apparatus includes an articulated arm having at least two link elements connecting a contacting tip element to the support for rotational movement about a plurality of mutually angulated axes. By means of the arm articulation, the contacting tip element can be moved to arbitrary locations within a defined volume. Potentiometers are provided for measuring each of the angles of rotation about the mutually angulated axes. These potentiometers generate signals which collectively determine the coordinates of the location of the tip element. Embodiments are disclosed having three and four degrees of freedom.