OPTIMAL SYNTHESIS, VERIFICATION AND IDENTIFICATION OF A HIGH-PERFORMANCE INERTIAL ISOLATION SYSTEM

摘要

Measuring small forces or impulses needs a mechanical system in an isolated inertial frame. The isolated system has to be set in a "free-fall" condition along one or more so-called "soft" degrees of freedom (DOF). Such a condition is achieved by means of dedicated mechanisms acting as inertial isolation systems. In the LISA Pathfinder space mission, a critical phase has been identified when a mechanism must release an object in free-fall conditions inside the spacecraft. A ground-based experiment reproducing this free-fall condition has been planned to verify the feasibility of such a phase. For this experiment, the Roberts linkage has been proposed as a suitable mechanism to realize an inertial isolation stage with two soft DOFs on the horizontal plane. The key feature of the linkage dynamic response is the virtual surface generated by a reference point belonging to its suspended part. The geometry of the linkage has been optimized in order to conform the virtual surface to the required free-fall level of the suspended system. A prototype has been realized and the virtual surface has been measured. Through a reverse engineering approach the characteristics of the surface geometry affecting the mechanism performance have been extracted. By comparisonbetween nominal and actual surfaces, information is drawn on the mechanism quality and about the adjustment procedure to improve its response.