TPF-C Technology Plan - Exoplanet Exploration Program - NASA

Plan for Technology Development
7.5.2 Precision Hexapod
Scope
The testbed development begins in pre-Phase A with design work and requirements definition.
By the end of pre-Phase A the metrology sub-system will demonstrate 15-nm measurement. In
Phase A, components and full hexapod systems will be acquired where possible, and designed
and built where necessary to develop a baseline concept. In Phase B, the EM of the hexapod
system will be designed, fabricated and demonstrated to meet performance requirements. This
characterization facility will be used during the I&T program to verify the performance of the
flight hexapod. The schedule for the precision hexapod is given in Table 7-12.
State of the Art TRL 3
A hexapod built by JPL for SIM in 1997 was designed for a 20 kg payload. It used precision ball
screw actuators to achieve a piston accuracy of 1 micron, a pointing accuracy of 3 arcsec, a
pointing range of 15 degrees from nominal, and a maximum travel range of 8 cm. The hexapod
was designed with low CTE materials and the struts were conductively decoupled from its
surroundings to aid with thermal stability.
Table 7-12. Precision Hexapod Schedule
Planned
Completion
Date
Pre-Phase A
Q4 FY05
Pre-Phase A
Q2 FY06
Phase A
Phase B
Phase C/D
Planned Activities Performance Targets TRL
Planning of the testbed Clearly define the goals and uses of the testbed 3
Proposed initial development of
the test-bed facility (pending
availability of resources)
Characterization of actuators and
hexapod systems
Characterization of EM hexapod
system
Utilize the facility to perform
initial verification of the flight
Hexapod system
Demonstrate the ability to measure 6 degrees of
freedom to a level of 15 nm over a 5 mm range
Procure/fabricate actuator and hexapod systems and
characterize using the facility
Facility used to verify performance of an EM
hexapod system
Facility is used to verify the performance of the
flight hexapod system
4
5
5
6
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