A high precision, dual drive system has been designed and developed for the Wide Field Upgrade to the Hobby-Eberly Telescope at McDonald Observatory in support of the Hobby-Eberly Telescope Dark Energy Experiment. Analysis, design, and controls details will be of interest to designers of large scale, high precision robotic motion devices. The drive system positions the 19,000 kg star tracker to a precision of less than 5 microns along its 4 meter travel. While positioning requirements remain essentially equal to the existing HET, tracker mass increases by a factor greater than five. The 10.5 meter long tracker is driven at each end by planetary roller screws, each having two distinct drive sources dictated by the desired operation: one slowly rotates the screw when tracking celestial objects and the second rotates the nut for rapid displacements. Key results of the roller screw rotordynamics analysis are presented in the paper, “Design and development of a high precision, high payload telescope dual drive system,” coauthored by Michael Worthington, Timothy Beets, Joseph Beno, Jason Mock, Brian Murphy, and Brian South (UTCEM) and John Good (UT McDonald Observatory) and presented at the SPIE Astronomical

Telescopes and Instrumentation 2010, San Diego, California, 27 June-2 July 2010).

A description of the complex bearing arrangement providing required degrees of freedom as well as the impact of a detailed Failure Modes and Effects Analysis addressing necessary safety systems is also presented in the paper. Finite element analysis results demonstrate how mechanical springs increase the telescope’s natural frequency response by 22% and critical analysis and resulting design is provided.

For more information please contact Michael Worthington.

detail vew track drives

Detail veiws of X slew and track drives (far right imate)

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