A single-axis tracking interferometer to measure two-dimensional error motions of machine tools and industrial robots

A conventional tracking interferometer has two rotary axes to regulate the laser beam direction, such that the 3D position of a target retroreflector can be measured from the laser beam direction and the distance to it. The rotary axis geometric errors can directly contribute to its measurement uncertainty, which result in higher assembly and calibration cost. This paper proposes a single-axis tracking interferometer. Since rotary axis geometric errors give only a negligibly small influence in this single-axis configuration, its assembly cost can be significantly reduced. This paper presents its applications to (1) 2D error motions of two linear axes on a machine tool and (2) the angular positioning deviations of two rotary axes on a planar robot arm. They are not merely a 2D version of the well-developed multilateration, but enable a new quick test to measure the 2D error motions. The uncertainty assessment is also presented.