Fiber Bragg Grating (FBG) sensors sense the change of temperature or strain by detecting the wavelength shifted
reflected by the Bragg grating carved on a fiber. Aiming at measuring tension of cables, we did a lot of experiments with
FBGs, testing its loading characteristics, temperature response, repeatability, consistency of different sensors, and long
term stabilization. When analyzing data, we find that environment temperature has a serious influence to the result. So
we use temperature compensation with a temperature sensor. Then we proceeded same experiments with traditional force
sensor under the same condition, compared their result and analyze the advantages and disadvantages of the two kinds of
sensors in the measurement of cable tension. At last, we made some prospect on FBG using on cable tension
measurement.
KEYWORDS: Reflectors, Cameras, Photogrammetry, Spherical lenses, Telescopes, Calibration, Retroreflectors, CCD cameras, Radio telescopes, Control systems
China has embarked on a project to build the world's largest radio telescope, the Five hundred meter Aperture
Spherical Telescope (FAST), in a karst depression in southwest Guizhou Province. The telescope is of a
modified Arecibo type. We suggest an active main reflector that is spherical in the neutral state but the
illuminated aperture of 300m in diameter would be adjusted into a proper paraboloid such that a simple feed
could be used at its focus, since the "spherical correction" has be done on the ground. The feed cabin at the
focus is supported and driven directly by cables controlled by computer, which avoids a heavy and expensive
feed supporting system. Newly developed method and technology for determining the spatial position of 2400
nodes on the main reflector of the FAST are introduced in this paper. Base on the measurements of the position
of node under which the down cable are linked, a loop feedback control enables accurately driving the spherical
reflector deformed to paraboloid. The key technique of this implementation is the precise measurement of
2400 nodes. In this article, we introduce the scheme of simplified photogrammetry aiming at no lateral shift
situation; we analyse the influence of lateral shift; and considering lateral shift, we propose a scheme using
rotation platform plus double-eye camera to accomplish the dynamic measurement of the reflector. The result
of analysis and testing shows the feasibility and effectivity of the scheme of measurement.
KEYWORDS: Sensors, Control systems, Operating systems, Resistance, Spherical lenses, Data acquisition, Control systems design, Telescopes, Amplifiers, Telecommunications
To meet the need of feed control, Cable Tension Real-time Measure System based on RTLinux was established. And the
system is used to keep those cables healthy and safe. Resistance tension sensors are used in the system, and differential
holodesmosomes are also used in the system to raise system performance. Bad data checking in software raised the
performance of anti-interference.
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