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XYZ mechanisms
An
innovating XYZ mechanism has been designed and space qualified within 16 months
for MIDAS instrument of ROSETTA space mission under ESA/ESTEC contract.The
function of this mechanism is to ensure the scanning motion of an Atomic Force
Microscope (AFM)aiming at analyzing the dust of Wirtanen comet.The objective
for ESA/ESTEC was to get a lightweight stiff nano-resolution stage able to
produce a stroke in the volume [0;+100 レm ] x [0;+100 レm ] x [0;+8 レm ]. At
first,the engineering model (EM)of an XY stage has been designed and tested.
The design work has been performed with ATILA and I-DEAS (Figure 4.8).The general concept is shown on the Figure 4.8.It uses 8 Actuators placed in the X and Y directions to provide the required strokes and acts also for the guiding functions,by forming a parallelogram.
Flexural hinges are used to decouple the X and Y axis.The construction takes benefit from the planar structure.The shells and the central moving frame were made in one stainless steel part.This is an advantage for the weight but also for reducing the assembling costs. In the Qualification Model (QM)(Figure 4.9 and Figure 4.10)a customized lightweight Parallel Pre-Stressed Actuator (PPA)controlled by strain gauges has been implemented on the Z axis to replace a too heavy standard Direct Piezo Actuator.
Two shape memory alloy (SMA)Actuators have also been implemented for the latching mechanism.This stage has passed the vibrations tests at the qualification level,which are higher than usual values, as well as other tests,including a wider temperature range and latching tests.A Flight Model (FM)has been constructed for implementation in MIDAS and hopefully will fly in 2003 on ROSETTA (Figure 4.11). An industrial version of the concept,the XY200M,is also available (Section 10).The concept used for Rosetta mechanism has been simplified by eliminating functions that are specific to space requirements,in order to reduce its cost.
An other example of XYZ mechanism developed for an optical application is given on the Figure.This mechanism is able to perform any stroke in the volume [-100,+100 レm ] x [-100,+100 レm ] x [0,200 レm ].It is entirely based on standard components.It combines a standard XY200M stage based on 4 APA200M for centered XY displacements with a set of 3 APA200M for Z displacement.