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Description
The objective is to develop a control approach for the active shaping of large membrane
structures using active materials. Membrane mirrors are thin, flexible optical surfaces for
satellite lenses that are lightweight and can be stored compactly. These types of mirrors
are expected to enhance inflatable space technology by providing quality optical imaging
while reducing current weight and storage requirements. Membrane mirrors, however,
require active surface control for proper imaging and are subject to various disturbances
(including large thermal gradients and internally induced excitation) that can lead to
degraded performance. Active materials, such as piezoceramics, have been proposed as a
means of providing disturbance rejection via distributed actuation; the idea is to attach a
number of actuators along the outer rim of the optic and actively control them to produce
a desired motion. However, unlike typical piezoelectrically actuated structures, due to the
properties of the membrane, the introduction of the piezoceramic significantly alters the
dynamic behavior of the membrane structure. Here we propose a novel method of
simultaneous shape and vibration control based on the dynamical theory of partly
specified motion. The basic idea behind this method is to solve for the open-loop control
input from the membrane-actuator model that achieves the approximate desired shape.
The open-loop control is then augmented by a feedback loop that accounts for
uncertainties due to modeling errors and external vibration disturbances. We propose to
conduct numerical simulations and a simple small-scale experiment to test the control
method.
Active membrane shaping is an important problem for the employment of new ultralightweight,
ultra-large and deployable telescope architectures. NASA JPL is at the
forefront of this effort with several ongoing projects, including the Dual Anamorphic
Reflector Telescope (DART); this new telescope architecture consists of a single aperture
formed from two cylindrical parabolic reflectors. The system is ideally suited to use
tensioned membranes for the reflective surface. The problem of active shape control
remains a challenge and is an ongoing effort at JPL. The research effort proposed here is
intended to provide a means to foster interaction with NASA JPL and to develop
collaborative relations. The results generated from this work will be useful in forming
shared objectives with JPL with the ultimate goal of pursuing collaborative research
projects. As indicated in the attached letter, Dr. Greg Agnes of NASA JPL has expressed
interest in discussing future collaborations in the area of adaptive structures technology.
The proposed effort will provide a basis for successful interaction.
Status | Finished |
---|---|
Effective start/end date | 1/1/11 → 12/31/11 |
Funding
- KY Council on Postsecondary Education
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Projects
- 1 Finished
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EPSCoR: Match for NASA Kentucky Space Grant
Smith, S. (PI) & Lumpp, J. (CoI)
KY Council on Postsecondary Education
8/1/10 → 6/7/16
Project: Research project