29 October 1998 Inchworm motor developments for the Next-Generation Space Telescope (NGST)
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Abstract
A new NGST InchwormR motor design is described that meets the demanding actuator requirements of the Next Generation Space Telescope. The classic Inchworm motor does not function at cryogenic temperatures. The interference fit between the motor and shaft gets tighter and breaks the clamps and 80 percent of piezoelectric (PZT) movement is lost at 20 degrees K. The NGST Inchworm concept maintains a constant fit over a wide temperature range and the loss of PZT motion is compensated for by adding extra PZT material or potentially by incorporating new cryogenic active materials that are currently being developed by other companies. Another significant improvement of the NGST Inchworm is the ability to hold position when power is removed (i.e. zero charge on all actuators) with zero PZT creep. This makes it possible for the NGST Inchworm and electronics to dissipate zero power when holding position for days or weeks. The NGST Inchworm will have a new clamp design that has at least ten times lower clamp 'glitch' than the classic Inchworm. Low clamp glitch makes it possible to move to a desired position with nanometer resolution and deactivated the motor without disturbing the output position more than a few nanometers.
© (1998) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
David A. Henderson, John C. Fasick, "Inchworm motor developments for the Next-Generation Space Telescope (NGST)", Proc. SPIE 3429, Current Developments in Optical Design and Engineering VII, (29 October 1998); doi: 10.1117/12.328551; https://doi.org/10.1117/12.328551
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