Machining, Measurement, and Control Laboratory

Non-contact R-test for Dynamic Measurement on Five-axis Machine Tools
Cefu Hong, Soichi Ibaraki

The R-test is a new instrument to measure three-dimensional displacement of a precision sphere attached to a spindle relative to a work table by using three displacement sensors, and its application to error calibration for five-axis machine tools has been studied in both academia and industry. For the simplicity in calculating the sphere center displacement, conventional R-test devices use contact-type displacement sensors with a flat-ended probe. However, the conventional contact-type R-test may be subject to potentially significant influence of the friction or the dynamics of supporting spring particularly in dynamic measurement. In this paper, a non-contact R-test with laser displacement sensors, as well as a new algorithm for calculating three-dimensional displacement of sphere with non-contact displacement sensors, is proposed. For evaluating the proposed algorithm, measurement accuracy with non-contact R-test constructed by laser displacement sensors of different measuring principles is investigated separately.
Keywords: Non-contact R-test, Dynamic measurement, Five-axis machine tool, Laser displacement sensor.