The six-degrees-of-freedom attitude measurement instrument for the large aperture mirror using the prepressing sensors and flexible supporting.

Abstract

To achieve precise measurement of a large aperture mirror, a six-degrees-of-freedom (6-DOF) measurement instrument is designed to monitor and calculate the real-time attitude of the mirror. Magnetoelectric displacement sensors are prepressed, and a flexible sensor supporting is designed to achieve high-accuracy measurement. The relationship between 6-DOF displacements of the mirror and the six sensor values can be obtained using the coordinate system transformation and Jacobian matrix. The Newton's iteration method is used to decouple the strong coupling measurement system, and 6-DOF displacements are obtained. The displacements directly measured by using laser sensors are compared with the calculated values in the experiments, the minimum average error of the measured displacement is 1.87%, and the mean difference of the displacement is 0.43 µm.