|
Developed by the National Physical
Laboratory for the European Space Agency, the micro-vibration platform is used
to measure internal vibrations and test satellite components under a range of
controlled vibration conditions. This ensures they can operate correctly in a
satellite environment without affecting other sensitive systems. The platform
is so sensitive it can measure the force of a single dropped feather and reduce
the effects of vibrations coming from waves of the nearby North
Sea.
The European Space Agency (ESA) has added a
micro-vibration test instrument, developed by the National Physical Laboratory
(NPL), to its satellite testing facilities. NPL is the UK’s National
Measurement Institute, developing and maintaining the national primary
measurement standards. The instrument measures vibrations generated by
satellite subsystems to quantify their effects on images and measurements made
from space. This facility is the result of five years of collaboration between
NPL and ESA.
Vibrations onboard a satellite can be caused by
common instruments and mechanisms, such as spinning reaction wheels, solar
array drives, and rotating cryocoolers. ESA needed to be able to measure and
correct for these jitters and vibrations to improve the accuracy of its
Earth observations. This required the simulation of satellite components
under a range of controlled vibration conditions.
The NPL won a tender
to design a system for the European Space Agency, which required a very high
level of performance, said Dan Veal, Senior Research Scientist with the
National Physical Laboratory in the United Kingdom. The system was required to
measure very low frequency related to very low force. ESA needed a better way
to check satellite components for these micro-vibrations, and to what
effect they might disrupt a spacecraft.
Measurement Platform Supported by a
Vibration Isolation Platform
NPL developed a platform which can
characterize any force produced by a satellite component weighing up to 150
pounds, added Veal.
The micro-vibration platform can measure vibrations
to an unprecedented degree of accuracy. It is so sensitive it can measure the
force of a single dropped feather. Sometimes housed in a vacuum chamber to
simulate space conditions, when used in air, the system is enclosed in a tent
to limit perturbations caused by airflow.
The platform is built as a
structure of two main levels: 1) a lower vibration isolation platform to
cancel disturbances coming from the ground, and 2) an upper measurement
platform.
Lower Vibration Isolation Platform
The lower vibration isolation platform uses a passive Negative-Stiffness
vibration isolator, coupled with three highly sensitive active seismometers
that control actuators, to sense ground vibrations coming into the system. The
seismometers are designed to measure up to 0.3 hertz. Coupled with the
Negative-Stiffness isolators, the passive/active system enables vibration
isolation down to 0.1 Hz. This system significantly reduces the effects of the
vibration coming from sources, such as footsteps even waves from the nearby
North Sea, ensuring a quiet environment for the measurement platform that is
mated on top.
We developed the lower vibration isolation platform around
Minus K’s Negative-Stiffness isolators because they are capable of
passively isolating vibrations down to 0.5 Hz, explained Veal. This was very
important for our low-frequency application. But we also selected
Negative-Stiffness because it is vacuum compatible.
Essentially, we
stripped the Negative-Stiffness isolators down to their core systems, then
augmented them with active seismometers connected with a custom interface,
explained Veal. This enabled us to get down to 0.1 Hz isolation.
Full article...
|
Check out previous Educational
Giveaway winners:
