Using a commercial off-the-shelf (COTS) solution for high performance computing (HPC) in active and adaptive optics real-time control in a large telescope.
Combining the NI LabVIEW graphical programming environment with multicore processors to develop a real-time control system.
For a size comparison, two humans and a car are positioned next to the E-ELT.
At the European Southern Observatory (ESO), an astronomical research organization supported by 13 European countries, the next project on our design board is the European Extremely Large Telescope (E-ELT), which is currently in the design and prototyping phases.
The M1, the primary mirror for the E-ELT, is a segmented mirror that consists of 984 hexagonal segments, each weighing nearly 330 lb with diameters between 1.5 and 2.0 m. These mirror segments comprise 3,000 actuators and 6,000 sensors. To control the system, LabVIEW must read the sensors to determine the mirror segment positions and, if the segments move, use the actuators to realign them. LabVIEW must compute a 3,000 by 6,000 matrix by 6,000 vector product and complete this computation 500 to 1,000 times per second to produce effective mirror adjustments.
Sensors and actuators also control the M4 adaptive mirror, a thin deformable mirror 2.5 m in diameter and spread over 8,000 actuators. This problem is similar to the M1 active control, but instead of retaining the shape, we must adapt the mirror’s shape based on measured wavefront image data. The wavefront data maps to a 14,000-value vector, and we must update the 8,000 actuators every few milliseconds, which requires about 15 times more control computation than the M1.
NI engineers are simulating the layout and designing the control matrix and control loop. M1 and M4 control requires enormous computational ability, which NI engineers approached with several multicore systems. LabVIEW offers multicore processing using configurable, off-the-shelf solutions, making it a very attractive solution for this problem.
NI engineers proved that we can use LabVIEW and the LabVIEW Real-Time Module to implement a COTS-based solution and distribute multicore computation control across 128 cores for real-time results.
– Dr. Jason Spyromilio, European Southern Observatory
1. Additional Resources
This article first appeared in the Q1 2009 issue of Instrumentation Newsletter.