Segment Positioning System

SALT continuously embarks on ensuring our technology stays up to date and this is accomplished through our asset renewal plan.

The most recent project was to replace the obsolete Segment Positioning System (SPS) controllers with new efficient controllers. This would also help to minimize the downtime experienced with the old system. The SPS controls the primary mirror segments’ tip, tilt and z position and is commanded by the Mirror Alignment Control System (MACS) to retain the Primary Mirror’s spherical shape either through CCAS tower mirror alignment, or the SAMS edge sensor measurements. This meant purchasing new customized controllers that would be controlled via the network compared to the previous serial interface control which was problematic.

A new custom igloo was built to house these controllers with optimal cooling control, as well as rewriting the software from scratch to command the controllers, and a new Human Machine Interface (HMI) that was designed based on the requirements of all the users of the system.

The new HMI is more user friendly with the backend designed for better analysis of the performance of the system. During the SALT Shutdown in February/March, a huge task was undertaken to install the new igloo with cooling, install all the controllers, and to move 271 cables from the old controllers to the new controllers in the new igloo. Testing continued between the SALT Operator, Mirror Team, and SPS Project Team and was a huge success. The new system also allows for better fault finding and logging should any problems be experienced. More than a year went into the planning and design of the new system with a dedicated SALT team, some working in their spare time, to make this happen.

New SPS Contollers Rack.