Deep in the rural Chinese county of Pingtang, in Guizhou Province, lies the largest radio telescope on the planet. The Five-hundred-meter Aperture Spherical radio Telescope (FAST) is the size of 30 football fields, with a fixed 500 m (1,600 ft) diameter dish constructed in a natural depression in the landscape. It is currently on a trial run, but has already successfully found the millisecond pulsar in the Milky Way.
The FAST project includes three major independent innovations, and one of them is the Optical-electro-mechanical light-weight feed support system, which maneuvers the world’s largest cable-driven parallel robot with a span of 600m and a large Stewart platform in the focus cabin to achieve high positioning precision (10mm) of those feeds.
Since 2012, Rui Yao, Associate Research Fellow at the National Astronomical Observatory of the Chinese Academy of Sciences, has been the head of the focus cabin system, which is the core component of FAST. “If FAST is the eye of heaven, then the focus cabin system would be the pupil of this eye. It makes us ‘see’ things in a much clearer and focused manner,” Yao said.
Over the past 13 years, she has completed two theoretical innovations based on robotics and mechanism theory:
She proposed a set of evaluation indices to measure the tension characteristics of the large span cable-driven parallel robot. This is the first time numerical methods are being used to describe the relationship between cable tension distribution and control precision.
She also created a precision design and compensation method for large hybrid robots and successfully applied it to FAST, which is used in the focus cabin to realize the millimeter level positioning accuracy in the range of hundreds of meters. It has made a great contribution to FAST to transition to the trial run stage.
Furthermore, and based on that theory, Yao and her team are expected to further improve the control accuracy of the focus cabin to expand the feed frequency band and the efficiency of astronomical observation.