A real time error measuring device for meso scale machine tools
Abstract This paper describes the development of a real time error measuring device for the simultaneous measurement of movement errors in straightness, yaw and roll in a linear machine stage. It was designed specifically for measuring errors in the spatial positioning of meso scale machine tool stages. The arrangement of the optical path and design of the optical elements make it easy install the device on a linear stage. Roll, yaw and horizontal straightness error motions are sensed using the reflection of a laser beam from a plane mirror. A nonlinear measurement model was derived and simulation analysis showed this could be linearized when the measurement angle error was smaller than 0.05deg. The measurement ranges of the proposed system are 30' for th x 20' for th y and 30 mm for the z axis. The measurement precision was verified using a laser interferometer and an electronic level and the accuracy of the angular error and straightness error measurements were found to be in the range of 0.25' and 0.5 mm respectively. The extended measurement uncertainties (95% confidence level) were: 0.46' for th x error motion; 0.46' for th y error motion; and 0.616 mm for straightness.