AO Controls: Status and Issues Erik Johansson, Jimmy Johnson, Doug Morrison and Ed Wetherell NGAO PD Team Meeting #6 Thursday, March 19, 2009

2 Controls Originally called non-RTC Controls --> renamed for simplicity Controls encompasses “everything but the kitchen sink”: control of all devices in the AO and Laser systems –Motion control: control of all movable devices in the system All optical stages, shutters, etc. Does not include position control of deformable or tip-tilt mirrors –Device control: control of all non-moving devices in the system requiring computer control Environmental control –Temperature, humidity, particulates Power control Camera control (setting parameters, not low-level CCD or focal plane control) DM and TT control –Any control required not including mirror positioning commands, e.g., control of drive amplifiers, mirror controllers, etc. RTC control: set up and operation of the RTC Laser system control Data server –Acquisition, guiding, offloading and pointing control –Instrument control: all coordination and sequencing required to use instrument with NGAO system –High level coordination and sequencing control of entire NGAO system

3 Major areas of effort Overall control system architecture Software architecture Sequencer design: Multi-System Command Sequencer (MCS), AO Sequencer, Laser Sequencer –Sequencers are main command processors and command sequencers used to control the system AO and Laser system SW design (SW not included in sequencers) Motion control architecture Motion control design, both HW and SW Data server design User interface design SW standards document

4 Control system architecture Control system architecture and SW architecture are deeply intertwined Distributed control system organized hierarchically Independent subsystems, but MCS is master Instrument does NOT control AO system and telescope –Instruments in current AO system do this –Troubleshooting is problematic –Instrument should be a subsystem of the overall NGAO system Each subsystem has levels of control within it

5 Distributed control system

6 Hierarchy of controls

7 Software architecture SW architecture “views” –Logical view Shows object decomposition –Development view SW module organization Shows interaction of SW components –Layered view Shows interaction of SW components in layered hierarchy –Physical view Maps SW to HW Preliminary mapping during PD phase Full definition during DD phase –Process view Shows SW decomposition to tasks, threads, processes This view will be defined during the DD phase

8 Logical view

9 Development view (1)

10 Development view (2)

11 Development view (3)

12 Development view (4)

13 Layered view Middleware is the SW that implements the distributed control system Wire protocol is the communications protocol used by the middleware Middleware API implements the programmer interface to the middleware For example, in the Data Distribution Service (DDS), DDS is the middleware and Real-Time Publish-Subscribe (RTPS) is the wire protocol. Middleware Wire Protocol Middleware API Sequencer User Interface Health Monitoring Utilities

14 Middleware evaluation We are evaluating several different middleware technologies for use in NGAO Evaluation topics: –Services: Logging Data archiving Alarming Health monitoring Configuration Telemetry Administration Event support User interfaces –Language support Python Java C/C++ –Communication Point to point Multicast Data support Synchronous Asynchronous Publish-subscribe –Application development Inheritance Loosely coupled Location transparency Type mapping –Performance Evaluations on 3 PCs VMWare to easily switch between environments

15 Middleware candidates DDS – Data Distribution Service –Uses a Publish-Subscribe paradigm –Is widely used in DoD, so is robust –Available from several vendors (RTI, PrismTech, Gallium) –DDS is an OMG standard ICE – Internet Communication Engine –From same group that developed CORBA –Open source (free) –Lots of tools available Advanced Technology Solar Telescope (ATST) Common Services Framework –CSF is main controls SW for ATST –ATST are happy to share CSF with us (free) EPICS –We are keeping EPICS as a fallback option –We will support (legacy) EPICS interfaces as required through bridges Several other candidates have already been rejected: –TINE –TANGO –OpenDDS –OCERA (open source DDS)

16 Sequencer concept Command – response design pattern –Encapsulates action, parameters, response Compound tasks (workflows) are straightforward to build –Simple syntax will allow SAs to write scripts Thread pool to handle multiple asynchronous tasks Easy to build UI around

17 Motion control architecture KAON 643 Motion Control Architecture Study –Devices fall into natural groupings based on location and control complexity –Want to match control complexity and cost to the device groupings –No “one size fits all” solution –Cabling will be a real challenge –Architecture will likely be a combination of centralized and distributed components –We have taken into account the device reductions resulting from the build-to-cost effort Main result is reduced device count  savings in I&T No group of devices completely eliminated  only modest savings in NRE –We need more information: Finalization of device specs: speed, accuracy, payload weight, etc. Specs on thermal enclosure Device lifetime requirements

18 Device groupings (0) Shutters –simple in/out devices with very loose positional requirements –actual position when moving is not required (1) Low precision, non-tracking –moved during configuration, not during an observation –a dichroic or fold, for example (2) Medium precision, non tracking –moved during configuration, not during an observation –aligning a fold (tip/tilt) or other component (3) High precision, non-tracking –moved during configuration or acquisition, not during an observation –aligning a lenslet or focusing a unit (4) Tracking –synchronized to external inputs, constantly moving –ADCs, rotators (5) Extremely high precision (non)tracking –coordinated motion with other DOF(s), possibly tracking –Field steering mirrors, focus adjustment (6) Pickoff arms - coordinated high precision (non)tracking –most demanding DOF, coordinated motion with other DOF(s), synched to external inputs –spatial position constraints, based on static and dynamic obstacles, to avoid collision

19 Spectrum of device types

20 Location of NGAO motion control devices

21 Distribution of devices in the NGAO system

22 Motion control recommendations Architecture: –Centralized control for high-precision tracking devices –Distributed control for other devices Consider device multiplexing for type 0 devices to reduce control infrastructure Use smart motors for distributed control where possible. More analysis of the thermal constraints is required. Control components should be specified based on device requirements. “One size fits all” will be too costly and may not be feasible. HW selection should be done in collaboration with SW designers HW should support maintenance and troubleshooting. Devices in cooled AO bench should require minimum support. Careful considerations must be taken to minimize EMI. Use COTS controllers and packaging to reduce overall system cost. Need better device specifications to proceed: Device Description Sheets. Now is the time to begin collaborations with the design teams.

23 Issues Lack of information has been the biggest obstacle to date. Now that B2C effort is drawing to a close, it is time to begin closer collaborations with the other design teams. We need as much information as possible on all the devices to be used throughout the system. We will be calling to set up meetings/teleconferences to kick off the process and envision many “working” conferences and calls in the future.