BIG motion: Ultra-precise positioning for the largest telescope in the northern hemisphere

After seven years of construction, the largest optical telescope in the northern hemisphere, the Gran Telescopio Canarias (Grantecan) on La Palma, Spain, has begun trial operation. Heidenhain model ERA 780C angle encoders are being used to position the telescope. The telescope rotates about two axes: elevation (vertical motion) and azimuth (horizontal motion); earth motion also requires compensation during the sometimes hour-long observations.

04/24/2008


Schaumburg, IL — After seven years of construction, the largest optical telescope in the northern hemisphere, the Gran Telescopio Canarias (Grantecan) on La Palma, Spain, has begun trial operation. Heidenhain model ERA 780C angle encoders are being used to position the telescope — a solution that has already proven itself in numerous telescope projects. The telescope rotates about two axes: elevation (vertical motion) and azimuth (horizontal motion). In addition, the motion of the earth has to be compensated during the sometimes hour-long observations.
The angle of the azimuth axis is measured over a diameter of about 15 meters, which requires a scale tape with a length of 48.48 meters. 1,212,000 lines with the scale-tape grating period of 40Calibration and compensation of systematic errors bring a system accuracy of 0.06 arc secs (1.7E-5º) over 13.2°. Each scale is installed in a slot about the respective axis of motion and is provided with a suitable number of measuring heads.
The 105 million euro system is now in a test phase lasting one year. The hyperbolic telescope mirror consisting of 36 hexagonal segments will be expanded segment by segment until it reaches the total diameter of 10.4 meters. At the same time, all instruments will be adjusted. When ready for operation, the telescope will focus four million times more accurately than the human eye. It will enable astronomers to detect more details than ever before.
Edited by C.G. Masi , senior editor
Control Engineering Machine Control eNewsletter
Register here and scroll down to select your choice of eNewsletters free .





No comments
The Engineers' Choice Awards highlight some of the best new control, instrumentation and automation products as chosen by...
The System Integrator Giants program lists the top 100 system integrators among companies listed in CFE Media's Global System Integrator Database.
The Engineering Leaders Under 40 program identifies and gives recognition to young engineers who...
This eGuide illustrates solutions, applications and benefits of machine vision systems.
Learn how to increase device reliability in harsh environments and decrease unplanned system downtime.
This eGuide contains a series of articles and videos that considers theoretical and practical; immediate needs and a look into the future.
Big Data and IIoT value; Monitoring Big Data; Robotics safety standards and programming; Learning about PID
Motor specification guidelines; Understanding multivariable control; Improving a safety instrumented system; 2017 Engineers' Choice Award Winners
Selecting the best controller from several viewpoints; System integrator advice for the IIoT; TSN and real-time Ethernet; Questions to ask when selecting a VFD; Action items for an aging PLC/DCS
This digital report will explore several aspects of how IIoT will transform manufacturing in the coming years.
Motion control advances and solutions can help with machine control, automated control on assembly lines, integration of robotics and automation, and machine safety.
This article collection contains several articles on the Industrial Internet of Things (IIoT) and how it is transforming manufacturing.

Find and connect with the most suitable service provider for your unique application. Start searching the Global System Integrator Database Now!

Future of oil and gas projects; Reservoir models; The importance of SCADA to oil and gas
Big Data and bigger solutions; Tablet technologies; SCADA developments
SCADA at the junction, Managing risk through maintenance, Moving at the speed of data
Automation Engineer; Wood Group
System Integrator; Cross Integrated Systems Group
Jose S. Vasquez, Jr.
Fire & Life Safety Engineer; Technip USA Inc.
click me