Large diameter drives for accurate
positioning of extended, flexible structures
The latest generation of giant telescopes is going to expand
the size of the known universe by an order of magnitude. To
succeed in this task, enormous structures such as teh Gran Telescope
of Canarias (GranTeCan) which are 30 mt tall, 20 mt wide and
with mass in the several hundred tons, need to be controlled
in position and speed with submicron accuracy, responding in
real time to large random perturntions such as wind buffeting.
The only way to achieve such a control accuracy is direct drive
of the entire structure. Phase Motion Control, over the years,
has become a recognized leader in this field with the development
of 2 to 20 mt diameter large direct drives, based on patented
arc shaped linear motor structures and segmented permanent magnet
rings.
Starting with the VLT project (1994) with the first 10 m diameter
motor, Phase successfully debveloped large drives for other
projects such as the VLT Auxiliary telescopes, ALMA radio antennae,
et. al. To date, the 18 m diameter, 180,000 Nm azimuth drive
of GranTeCan is the largest such realization. The experience
acqured in the control of large, flexible structures with direct
drives shows large direct drive to be a very viable, cost competitive
and super performing approach which will likely supersed large
rack and pinion, bbogie or friction drives un multimeter diameter
position control. |
