WANG Yong, TAO Ta-Ke, ZHOU Feng, ZHANG Li-Min. Type synthesis of 3-DOF parallel support system for telescope secondary mirror[J]. Editorial Office of Optics and Precision Engineering, 2013,21(11): 2860-2869
WANG Yong, TAO Ta-Ke, ZHOU Feng, ZHANG Li-Min. Type synthesis of 3-DOF parallel support system for telescope secondary mirror[J]. Editorial Office of Optics and Precision Engineering, 2013,21(11): 2860-2869 DOI: 10.3788/OPE.20132111.2860.
Type synthesis of 3-DOF parallel support system for telescope secondary mirror
To realize tip/tilt and focus adjustment for a telescope secondary mirror
several types of parallel support systems were designed and their dynamic characteristics and construct selection were analyzed. First
the screw theory was used to realize the type synthesis for 2R1T (two-rotation and one-translation degrees of freedom) parallel mechanisms with 3 symmetrical branches. 12 types of feasible mechanisms with the fewest joint in each branch
the smallest inertia and linear actuators were selected for the support systems. Then
the selected mechanisms were classified according to the actuating characteristics and constraint properties and the kinematics models were established respectively
including actuation models and constraint models. Moreover
ZXZ Euler angels were introduced to describe the orientation of moving platform and to simplify the description and analysis of orientation and parasitic motion for 2R1T parallel mechanisms. Finally
a 1.2 m telescope was taken as an illustrative example to calculate the parasitic motion induced by the constraints. The results indicate that 7 types of mechanisms with constraint force parallel to the static platform have smaller parasitic motions no more than 0.27 mm. The kinematic model and design results provide theory basis for the following analysis on accuracy and stiffness.
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