Uncertainty experiment for large scale measuring equipment

To make up the shortage of the traditional combined measurement which enlarge measurement range and improve accuracy only by mechanical combination and measured value fusion, the measurement model of the multi-joint measuring arm and the laser tracker are analyzed, and the key parameters affecting measurement uncertainty are extracted. Following the repeated measurements of static single point, the above key parameter influences on uncertainty distribution are evaluated synthetically. The experimental results show that the waist joint 1 exerts lesser influence on the terminal measurement uncertainty, less than 0.04 mm, because the stiffness and accuracy of the waist joint 1 are obviously higher than the other joints; joint 7 has the least influence on it, less than 0.03 mm, which meets the design aim for improving flexibility of measurement arm. The other joints have ascending influence on it, and the influence from the hinge joints gets greater than the rotational joints. The measurement uncertainty, which affected by the laser tracker horizontal and vertical azimuth, distributes symmetrically two sides of 90°.