Single-mass 6-DOF isotropic accelerometer with segmented PSD sensors

Abstract

This paper outlines the novel design of a single-mass six-degrees-of-freedom (6-DOF) accelerometer, distinguished by a high level of isotropy. The six spatial coordinates (three linear and three angular) of the movements of its proof mass and their derivatives are obtained from simple measurement of the linear displacements of specially chosen points in the proof mass. Calculation of the accelerometer's six acceleration components is then possible according to a specially developed mathematical algorithm. Exceptional isotropy of sensitivity is ensured by the symmetrical structure of the device's three subsystems (inertial, suspension, and measurement). The accelerometer's structural symmetry is imparted by the proof mass’ cubic shape and 24 elastic supports (springs with damping inserts) that are mounted along the x-, y-, and z-axes in threes at the cube's vertices. The measurement subsystem consists of six differential optical displacement sensors, symmetrically located facing the centers of the cube faces, and a light source mounted at the center of the cube. Each optical sensor is based on three-component position-sensitive detectors of the segmented type. Working prototypes of the isotropic 6-DOF accelerometer have been manufactured, adjusted, and tested.