NASA Technical Reports Server (NTRS) 20110002986: Attitude Estimation in Fractionated Spacecraft Cluster Systems

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by  NASA Technical Reports Server (NTRS)

Multiplexed Energy Coupler for Rotating Equipment
John H. Glenn Research Center, Cleveland, Ohio
A multiplexing antenna assembly can With N outer pieces and M inner This work was done by Xiaoliang Zhao of
efficiently couple AC signal/energy into, pieces, an effective N×M combination Intelligent Automation, Inc. for Glenn Re-
or out of, rotating equipment. The unit can be achieved in a multiplexed man- search Center.
only passes AC energy while blocking ner. The energy coupler is non-contact, Inquiries concerning rights for the com-
DC energy. Concentric tubes that are which is useful if isolation from rotating mercial use of this invention should be ad-
sliced into multiple pieces are assembled and stationary parts is required. Addi- dressed to NASA Glenn Research Center, In-
together so that, when a piece from an tionally, the innovation can operate in novative Partnerships Office, Attn: Steve
outer tube aligns well with an inner tube high temperatures. Applications include Fedor, Mail Stop 4–8, 21000 Brookpark
piece, efficient energy coupling is rotating structure sensing, non-contact Road, Cleveland, Ohio 44135. Refer to
achieved through a capacitive scheme. energy transmission, etc. LEW-18467-1
Attitude Estimation in Fractionated Spacecraft Cluster Systems
NASA’s Jet Propulsion Laboratory, Pasadena, California
An attitude estimation was examined In order to create such a system, how- served. Also developed was a navigation
in fractioned free-flying spacecraft. In- ever, it is essential to know what the nav- filter that can estimate the cluster atti-
stead of a single, monolithic spacecraft, igation capabilities of the fractionated tude if these conditions are satisfied.
a fractionated free-flying spacecraft system are as a function of the capabili- Each module in the cluster may have
uses multiple spacecraft modules. ties of the individual modules, and to either a startracker, a relative attitude
These modules are connected only have an algorithm that can perform esti- sensor, or both. An extended Kalman fil-
through wireless communication links mation of the attitudes and relative posi- ter can be used to estimate the attitude
and, potentially, wireless power links. tions of the modules with fractionated of all modules. A range of estimation
The key advantage of this concept is sensing capabilities. performances can be achieved depend-
the ability to respond to uncertainty. Looking specifically at fractionated at- ing on the sensors used and the topol-
For example, if a single spacecraft titude estimation with startrackers and ogy of the sensing network.
module in the cluster fails, a new one optical relative attitude sensors, a set of This work was done by Fred Y. Hadaegh
can be launched at a lower cost and mathematical tools has been developed and Lars James C. Blackmore of Caltech for
risk than would be incurred with on- that specify the set of sensors necessary NASA’s Jet Propulsion Laboratory. For more
orbit servicing or replacement of the to ensure that the attitude of the entire information, contact [email protected].
monolithic spacecraft. cluster (“cluster attitude”) can be ob- NPO-46962
Full Piezoelectric Multilayer-Stacked Hybrid Actuation/
Transduction Systems
Applications range from dynamic control and underwater detection to health monitoring and
use in acoustic structures.
Langley Research Center, Hampton, Virginia
The Stacked HYBATS (Hybrid Actu a - BATS is much stronger than the reso- elements makes an enhanced motion
tion/Transduction system) demo n- nance of a single element actuation only along the Z direction for Stacked-HY-
strates significantly enhanced electro- when the effective lengths of the two BATS. In order to dominate the dynamic
mechanical performance by using the kinds of elements match each other. length of Stacked-HYBATS by the nega-
cooperative contributions of the electro- Compared with the previously invented tive strain component, the area of the
mechanical responses of multilayer, hybrid actuation system (HYBAS), the cross-section for the negative strain com-
stacked negative strain components and multilayer Stacked HYBATS can be de- ponent will be much larger than the total
positive strain components. Both experi- signed to provide high mechanical load cross-section areas of the two positive
mental and theoretical studies indicate capability, low voltage driving, and a strain components. The transverse strain
that, for Stacked HYBATS, the displace- highly effective piezoelectric constant. is negative and longitudinal strain posi-
ment is over three times that of a same- The negative strain component will tive in inorganic materials, such as ceram-
sized conventional flextensional actua- contract, and the positive strain compo- ics/single crystals. Different piezoelectric
tor/transducer. The coupled resonance nent will expand in the length directions multilayer stack configurations can make
mode between positive strain and nega- when an electric field is applied on the a piezoelectric ceramic/single-crystal
tive strain components of Stacked HY- device. The interaction between the two multilayer stack exhibit negative strain or
28 NASA Tech Briefs, January 2011