A novel integrated sensing system (ISS) for monitoring motion errors of a precision linear slid

In order to improve the accuracy and reliability of scanning coordinate measure machines (CMM), the dynamic errors of the CMM axes have to be continuously monitored and compensated in the measurement process. This paper proposes a novel method and develops an Integrated Sensing System (ISS) to on-machine determine the three error components of a precision linear slide [1]: the straightness motion, the yaw and the roll under the effect of thermal distortion caused by friction and drive. The ISS is proposed for an illustrative model of a linear slide. It consist of eight distance sensors installed in a stationary stage, and five temperature sensors mounted at various parts of the working machine. The stationary stage is mounted opposite to the profile of the moving slide axis. The error separation algorithm of this novel method is based on Fourier series techniques. A pre-built thermal error model [2] based on thermal modal analysis [3] is used to obtain the deformations of different machine components. Then thermal looping [3] technique is used to estimate thermally-induced profile variations of the slide. The Fourier series technique is then applied to the pre-processed outputs of the distance sensors to obtain the profiles and the motion errors. Computer simulation confirmed the effectiveness of the ISS by comparing the calculated results with the pre-define inputs under thermal compensation [2] and no thermal compensation situations.