OPD Controller (As-built) Software Detailed Design
Contents
1. A Id opdcDB_DATA class v 2 1 2008 02 13 20 01 11 vltsccm Exp Zd SS who when what pduhoux 2000 04 06 created include 1sfDB DATA class CLASS BASE_CLASS opdcDB_DATA_UTC BEGIN ATTRIBUTE int32 seconds ATTRIBUTE int32 microsec ATTRIBUTE bytes32 isoString END CLASS BASE CLASS opdcDB DATA RMN FSU OPD Controller As built Software Detailed Design BEGIN ATTRIBUTE bytes32 name ATTRIBUTE double visibility 0 ATTRIBUTE double phase 0 ATTRIBUTE int32 phaseValid 0 ATTRIBUTE double coherence 0 ATTRIBUTE int32 cohValid 0 END CLASS BASE_CLASS opdcDB_DATA_INS BEGIN ATTRIBUTE bytes32 name PassThru ATTRIBUTE int32 enabled 0 ATTRIBUTE double rtOffset 0 ATTRIBUTE double zpdOffset 0 ATTRIBUTE double opdOffset 0 ATTRIBUTE double dlOffset 0 ATTRIBUTE int32 offsetValid 0 ATTRIBUTE int32 fringeDetected 0 ATTRIBUTE int32 targetDL U ATTRIBUTE double sign 1 ATTRIBUTE opdcDB DATA RMN FSU rmn END CLASS BASE CLASS opdcDB DATA CH DIAG BEGIN ATTRIBUTE double zpdRatio 0 ATTRIBUTE double idleRatio 0 ATTRIBUTE double lockCoherenceRatio 0 ATTRIBUTE double lockCophaseRatio 0 END CLASS BASE_CLASS opdc2. N A The process in charge of the fringe tracking algorithm is subject to hard real time RT constraints with high sampling freguency the design goal being 4kHz The process shall be activated periodically with a fixed low jitter repetition period No sample loss is allowed 2 4 Design Decisions The following list of design decisions DD is issued a priori from the above requirements Reference Dependency Decision DD 1 Constr 1 The software will be based on LSF DD 2 SR 1 amp The control algorithm will be implemented using TAC that features real time capabilities Constr 2 DD 3 Constr 2 The hardware structure will use 2 Power PC PPC boards to reduce the control algorithm K Pe CG DD 4 Constr 2 The real time algorithm shall be triggered at 2kHz by the TIM board interrupt and shall be evaluated at interrupt level to reduce the activation latency time DD 5 SR 1 amp The sign of the FTK control signal shall be computed from the current interferometer SR 2 configuration DD 6 DD 5 Selection of the tracking arm is not the responsibility of the OPDC In order to compute apply the adequate OPD sign the OPDC shall be told which is the DL and IC associated to the interferometer s tracking arm DD 7 SR43 The telescope chopping cycle is started on an absolute UTC time The OPDC only needs information on the chopping period duty cycle and telescope guiding window OPD Controller As built Soft
3. NOT MANUALLY EDIT THIS FILE 111111 J RK HK IK IK IK IK I I oko I I oko ko oko oko oko oko oko I I I I I I A Specific Z SETDLN IopdcSoftDevSetDelayLine FUNCTIO SETFSEN IopdcSoftDevSetFringeSensor FUNCTION SETFMOD IopdcSoftDevSetFTKMode FUNCTIO STRTCHP IopdcSoftDevStartChopping TASK opdSTRTCHP 30000 REGISTER STOPCHP IopdcSoftDevStopChopping FUNCTIO STRTFTK IopdcSoftDevStartFringeTracking FUNCTIO STOPFTK IopdcSoftDevStopFringeTracking FUNCTION STRTVTK IopdcSoftDevStartVibrationTracking FUNCTIO STOPVTK IopdcSoftDevStopVibrationTracking FUNCTIO oOo 5 2 Online Database Description Files 5 2 1 opdcDB_CONFIG class KKK KK KKK KK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK A kA k k E 8 0 VLT project L Id opdcDB_CONFIG class v 2 1 2008 02 13 20 01 11 vltsccm Exp who when what RENE pduhoux 2003 09 09 created LGE include 1lsfDB CONFIG class CLASS BASE CLASS opdcDB CFG RST BEGIN ATTRIBU ATTRIBU BEGIN Value 0 0 0 0 0 0 0 0 0 0 int32 order 2 Vector numer L double D TTRIBUTE Vector denom 10 double GIN Value 1 Dy 0 0 0 0 0 0 0 0 mp ti ti D U D CLASS BASE CLASS opdcDB CFG INS ZPD BEGIN ATT
4. Phase 0 it applies a variable offset designed to maintain the PRIMA group delay signal at around zero which allows tracking of the white fringe Ideally the lt openLevel gt and lt closeLevel gt thresholds are set to ensure the loop opens when the accuracy phase signal becomes low due to noise the lt timeout gt is favourably linked to the atmosphere coherence time i e the search shall be resumed if the loop has stayed open for a time long enough for the atmosphere to have moved the fringes out of FINITO PRIMA OPD field of view i e some 15m The initial ZPD search trajectory is a one dimension spiral When the search is resumed after fringes lost for some time the trajectory is triangular with a geometric progression of the amplitude and a constant rate SEARCH LOCK SEARCH Figure 5 ZPD search trajectory OPD Controller As built Software VLT SPE ESO 15420 4000 ESO Detailed Design 2 30 04 2008 18 of 30 4 1 4 Vibration Tracking Due to delay in the loop and the dynamical behaviour of the delay line high frequency disturbances are not rejected by the FTK loop Yet harmonic residual may be observed modeled as a sinusoidal signal with an amplitude frequency and phase VTK consists of observing the residual phase when the FTK loop is closed and adapting the parameters of the harmonic model in real time Multiple disturbances may be tracked by multiple instantiation of the function block implementing the a
5. e The FTK controller including model based VTK and Zero Path Difference ZPD search 4 1 2 Fringe Tracking with an Instrument Only i e VINCI or MIDI This function encompasses three blocks the instrument interface over RMN that is either configured to read data from VINCI or MIDI a gain that is either 1 or 1 depending on the interferometer tracking arm i e 1 if the tracking arm is entering the lab through IC3 and a DL interface over RMN that is connected to the tracking delay line the parameter of which is the DL identifier that is set to zero to disable this function In addition a constant block is used to enable static OPD offset compensation e g static OPD model error this offset is added to the instrument fringe offset signal 4 1 3 Fringe Tracking with FINITO or PRIMA incl ZPD Search FTK includes three parts a state machine driven by the fringe contrast SNR a central fringe acquisition procedure driven by the coherence and the actual position loop using the fringe phase COHERENCE_IDLE meout i USER H E Lef ZPD_SEARCH P SNR Coherence ee Only combined L algorithm END 1 m meout i X COPHASE IDLE COPHASE LOCK X USER SNR eeng gt Ee k SNR Figure 4 FTK state machine OPD Controller As built Software l VLT SPE ESO 15420 4000 ESO Detailed Design 2 30 04 2008 17 of 30 The FTK state machine transitions happen with FINITO SNR signal When F
6. handled automatically by the OPDC 4 3 3 Data Branch The data branch will at least gather the following attributes CH is either INS CH1 CH2 or PRM Point Attribute Type Description fsu String Current sensor on RMN CH enabled Boolean Set if the current channel is selected CH tracking Boolean FTK running or not CH targetDL Integer Tracking DL identifier CH sign Double Sign applied to the DL offset CH fringeDet Boolean Fringe detected flag CH rtoOffset Double FTK control signal OPD Controller As built Software VLT SPE ESO 15420 4000 E S O Detailed Design 2 30 04 2008 23 of 30 CH zpdoffset Double ZPD search offset CH opdoffset Double Total FTK ZPD offset CH dloffset Double Applied offset sign dependant CH rmn snr Double Data read on RMN CH rmn phase Double CH rmn phaseValid Boolean CH rmn coherence Double CH rmn coherValid Boolean chop frequency Double Relevant chopping parameters chop pvRatio Double chop onSky Boolean chop start seconds Integer chop start microsec Integer chop start isoString String chop stop seconds Integer chop stop microsec Integer chop stop isoString String OPD Controller As built Software VLT SPE ESO 15420 4000 E S O Detailed Design 2 30 04 2008 24 of 30 5 Appendix 5 1 CDT and CIT files 5 1 1 opdcPublic cdt J RRR IK IK ok ok IK I I I oko ok
7. 2008 15 of 30 4 Design Description This section presents the design of the opdc application software 4 1 TAC Real Time Algorithm 4 1 1 TAC Algorithm Structure The following diagram represents the TAC algorithm implementing the required functions INS ZPD Offset TIM 2kHz INS Tracking DLINS SS VTAlgo CH1 FINITO CH1 FTAlgo CH1 a Chop sequence Tracking DL CH1 ZPDSearch CH1 Figure 3 TAC Algorithm Schematic 1 DL 1 FTK channel only The function blocks appearing in green color are instantiated once for fringe sensor channel i e currently FINITO CH1 CH2 and PRIMA FSU The algorithm encompasses the following parts e An interface to the TIM board to configure periodic interrupts at 2kHz and provide the real time algorithm with absolute UTC to enable disable FTK with the chopping sequence e The definition of the telescope chopping sequence The block is configured with the chopping start and possibly stop time the chopping period duty cycle and telescope guiding window e The instrument interface over RMN to propagate the instrument fringe searching centering signal to the tracking DL with the adequate sign and a possible offset to cope with static OPD model error OPD Controller As built Software l VLT SPE ESO 15420 4000 ESO Detailed Design 2 30 04 2008 16 of 30 e The RMN interface blocks to read and write FTK signals e The RFN interface blocks to read PRIMA FTK signals
8. 2008 26 of 30 SYNONYMS opdcSoftDevStopFringeTracking FORMAT A PARAMETERS REPLY_FORMAT A REPLY_PARAMETERS H S ELP TEXT top Fringe tracking 5 1 2 opdcTest cdt J RRR KK kok IK kok IK I oko oko oko oko oko oko oko oko oko oko oko kok ok oko ok kok kok kok kok kok kok kok kok kok kok kok E S O VLT project Id opdcTest cdt v 2 1 2008 02 13 20 01 12 vltsccm Exp who when what bbauvir 2005 10 24 created Specific COMMAND STRIVTK SYNONYMS opdcSoftDevStartVibrationTracking FORMAT A PARAMETERS REPLY FORMAT A REPLY PARAMETERS HELP TEXT S G tart VTK COMMAND STOPVTK SYNONYMS opdcSoftDevStopVibrationTracking FORMAT A PARAMETERS REPLY FORMAT A REPLY PARAMETERS H S ELP TEXT top VTK Lif oOo 5 1 3 opdcSoftDev cit J RRR KK IK IK ok ke IK I I I oko oko oko oko oko oko oko ok ok kok kok ok ok kok kok I I I I I I A OK E S O VLT project Id opdcSoftDev cit v 1 10 1 21 2006 06 30 20 40 12 vltsccm Exp who when what bbauvir 2005 10 24 created OPD Controller As built Software i l LT SPE ESO 15420 4 ESO Detailed Design gt 098 30 04 2008 27 of 30 This file has been generated by a utility 11 LILII I DO
9. 5 Figure 45 ETK state EEN 16 Figure 5 ZPD searchitrajector yoiini nia a i ERE RT EE e 17 OPD Controller As built Software VLT SPE ESO 15420 4000 ESO Detailed Design 2 30 04 2008 6 of 30 This page has been left intentionally blank OPD Controller As built Software VLT SPE ESO 15420 4000 E S O Detailed Design 2 30 04 2008 7 of 30 1 Introduction 1 1 Purpose This document aims to present the design of the OPD Controller Software that is part of the VLTI Fringe Tracking FTK Facility 1 2 Scope This document shall first shortly describe the VLTI Fringe Tracking Facility and the function of the OPDC LCU therein It will then present the requirements and constraints associated to this software component Some design decisions are then issued from these requirements In order to ensure compliancy with LCU standard interface and behaviour described in AD 01 the code of this software component was first generated from LCU Server Framework LSF template and extended following the guidelines documented in AD 03 The LCC libraries messaging system and database are documented in AD 02 The implementation of the OPDC real time algorithm relies on Tools for Advanced Control TAC application described in AD 04 The design description section of this document mainly focuses on the application specific extensions brought to LSF and on the description of the real time algorithm In addition the reader should be
10. DB_DATA_CH_VTK BEGIN ATTRIBUTE int32 tracking 0 END CLASS opdcDB DATA INS opdcDB DATA CH BEGIN ATTRIBUTE bytes32 name Combined ATTRIBUTE int32 tracking 0 ATTRIBUTE opdcDB DATA CH VTK vtk ATTRIBUTE opdcDB DATA CH DTAG diag END CLASS BASE CLASS opdcDB DATA CHOP BEGIN ATTRIBUTE double freguency 0 ATTRIBUTE double pvRatio 0 ATTRIBUTE int32 onSkySeq 0 ATTRIBUTE int32 onTarget 1 ATTRIBUTE opdcDB_DATA_UTC start ATTRIBUTE opdcDB_DATA_UTC stop END CLASS lsfDB_DATA opdcDB_DATA BEGIN ATTRIBUTE bytes32 fsu FINITO CH2 ATTRIBUTE bytes32 mode SCIENTIFIC ATTRIBUTE opdcDB DATA CHOP chopping ATTRIBUTE opdcDB DATA INS INS ATTRIBUTE opdcDB DATA CH PRM ATTRIBUTE opdcDB DATA CH CH1 BEGIN ATTRIBUTE opdcDB DATA RMN FSU rmn BEGIN ATTRIBUTE by tes32 name FNT CH1 VLT SPE ESO 15420 4000 2 30 04 2008 29 of 30 OPD Controller As built Software VLT SPE ESO 15420 4000 E S O Detailed Design 2 30 04 2008 30 of 30 D U D TTRIBUTE opdcDB DATA CH CH2 EGI w D gt ATTRIBUTE opdcDB_DATA_RMN_FSU rmn BEGI ATTRIBUTE bytes32 name FNT_CH2 D U D TTRIBUTE opdcDB DATA CH PRM EGI w D gt ATTRIBUTE opdcDB_DATA_RMN_FSU rmn BEGI ATTRIBUTE bytes32 name FSUB D E END END 000
11. EUROPEAN SOUTHERN OBSERVATORY Organisation Europ enne pour des Recherches Astronomigues dans I H misph re Austral Europ ische Organisation fiir astronomische Forschung in der s dlichen Hemisph re ESO Technical A ted by ESO H ml dee Arch Ive VLT PROGRAMME 02 05 2008 VERY LARGE TELESCOPE OPD Controller As built Software Detailed Design Doc No VLT SPE ESO 15420 4000 Issue 2 Date 30 04 2008 Prepared Bertrand Bauvir Nicola Di Name Approved Thanh Phan Duc Name Released Francoise Delplancke Name Signature VLT PROGRAMME TELEPHONE 089 3 20 06 0 FAX 089 3 20 06 514 OPD Controller As built Software VLT SPE ESO 15420 4000 ES O Detailed Design 2 30 04 2008 2 of 30 CHANGE RECORD SECTION PAGE REASON INITIATION AFFECTED DOCUMENTS REMARKS 14 08 2006 First draft 16 08 2006 Second draft prepared for review 20 08 2006 Dedicated configuration database point 26 08 2006 Add instrument OPD offset of the night 31 08 2006 First release 30 04 2008 Update after integration of PRIMA changes and new vibration cancellation algorithm OPD Controller As built Software VLT SPE ESO 15420 4000 ESO Detailed Design 2 30 04 2008 3 of 30 TABLE OF CONTENTS 1 INTRODUCTION 7 1 1 Purpose 7 1 2 Scope 7 1 3 Applicable Documents 7 1 4 Reference Documents 8 1 5 Acronyms 8 2 FUNCTIONAL SPECIFICATION 9 2 1 Overview 9 2 1 1 About OPD Sign Conv
12. IC PAR DEF VAL AUTOTEST REPLY FORMAT A HELP TEXT Set fringe tracking operating mode H COMMAND STRTCHP SYNONYMS opdcSoftDevStartChopping FORMAT A PARAMETERS PAR NAME atTime PAR TYPE STRING PAR DEF VAL now PAR NAME freguency PAR TYPE REAL PAR DEF VAL 0 0 Means disable gt period of 0 0 also PAR_NAME pvRatio PAR_TYPE PAR DEF VAL 1 0 PAR NAME cycleType PAR TYPE STRING PAR RANGE ENUM A B BOTH PAR DEF VAL A REPLY FORMAT A REPLY PARAMETERS PAR NAME startTime PAR TYPE STRING PAR DEE VAL 2000 12 31T00 00 00 000000 HELP TEXT Start Chopping at the specified tim COMMAND STOPCHP SYNONYMS StopChopping FORMAT A PARAMETERS PAR NAME atTime PAR TYPE STRING PAR DEF VAL now REPLY FORMAT A REPLY PARAMETERS PAR NAME stopTime PAR TYPE STRING PAR DEF VAL 2000 12 31T00 00 00 000000 HELP TEXT Stop Chopping at the specified tim COMMAND STRTFTK SYNONYMS opdcSoftDevStartFringeTracking FORMAT A PARAMETERS REPLY FORMAT A REPLY PARAMETERS HELP TEXT S G tart fringe tracking COMMAND STOPFTK OPD Controller As built Software VLT SPE ESO 15420 4000 E S O Detailed Design 2 30 04
13. LTI Fast Link or Reflective Memory Network RMN MIDI and VINCI instruments are also present on the RMN to allow some level of fringe tracking without FINITO The OPDC does not support concurrent observations only one fringe sensor is enabled at a time It is capable of providing FTK for two baselines three telescopes i e triangle possibly collapsed at the same time when using FINITO as a fringe sensor The OPDC has been extended to handle one PRIMA FSU which is handled similarly as one FINITO channel Piston MT Vibrations Atmosphere Instrument Actuator FINITO Measurement Noise Figure 1 Schematic Layout of the Fringe Tracking Facility using FINITO The VLTI is suffering from atmospheric piston but also piston induced by vibrations of components in the optical train the latter being periodic it can be modeled and compensated by an adaptive vibration cancellation a k a tracking VTK algorithm see AD 07 The function of the OPDC is threefold e Propagate the VINCI or MIDI instrument fringe offset to the tracking delay line with adequate sign In this mode the OPDC acts only as a switchyard the instrument drives the tracking DL to search and center fringes e Provide FTK capabilities with FINITO or PRIMA In this mode the OPDC is responsible to search detect and track fringes using the signals measured by FINITO PRIMA e Provide VTK capabilities with FINITO PRIMA OPD Controller As bu
14. RIBUTE double offset 0 U D CLASS opdcDB CFG INS ZPD opdcDB CFG CH ZPD BEGIN ATTRIBUTE double sweep 0 ATTRIBUTE double period 0 U D OPD Controller As built Software VLT SPE ESO 15420 4000 E S O Detailed Design 2 30 04 2008 28 of 30 CLASS BASE CLASS opdcDB CFG CH CTRL ATTRIBUTE int32 type 0 ATTRIBUTE opdcDB CFG RST phase ATTRIBUTE opdcDB CFG RST coher END CLASS BASE CLASS opdcDB CFG CH FSM BEGIN ATTRIBUTE double detLevel 0 ATTRIBUTE double closeLevel 0 ATTRIBUTE double openLevel 0 ATTRIBUTE double timeout 0 END CLASS BASE_CLASS opdcDB_CFG_CH_VTK BEGIN ATTRIBUTE double dit 0 ATTRIBUTE bytes64 fileName Di z CLASS BASE CLASS opdcDB CFG INS ATTRIBUTE opdcDB CFG INS ZPD zpd Di el CLASS BASE CLASS opdcDB CFG CH BEGIN ATTRIBUTE opdcDB CFG CH VTK vtk ATTRIBUTE opdcDB_CFG_CH_ZPD zpd ATTRIBUTE opdcDB_CFG_CH_FSM Cam ATTRIBUTE opdcDB_CFG_CH_CTRL ctrl END CLASS lsfDB_CONFIG opdcDB CONFIG BEGIN ATTRIBUTE opdcDB_CFG_INS INS ATTRIBUTE opdcDB_CFG_CH PRM ATTRIBUTE opdcDB_CFG_CH CH1 ATTRIBUTE opdcDB_CFG_CH CH2 END 5 2 2 opdeDB DATA class KKK KK KKK KK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK kk kk kk kk E S O VLT project
15. TK is started the OPDC first applies a ZPD search trajectory i e the DL position is offset with respect to the blind tracking trajectory trajectory compensating the fringe motion due to earth rotation until the instantaneous SNR goes above a fringe lt detLevel gt threshold The FTK loop is then closed on the phase signal The implemented controller is of the form of a discrete transfer function up to the 9 order it allows to implement any kind of control e g simple PI or controller design coming from loop shaping or H2 Hoo optimization techniques In order to avoid driving the DL on noise FTK loop is paused resumed when the filtered i e moving average SNR signal goes below above a threshold with hysteresis i e lt openLevel gt lt lt closeLevel gt thresholds or when the chopping state is such that the telescopes are pointing to the sky target the states are denoted IDLE and LOCK If the SNR stays below the lt openLevel gt threshold for a certain lt timeout gt the loop is stopped and search trajectory is resumed Various algorithm types are available 1 Coherencer algorithm only using the coherence signal to acquire the central fringe 2 Cophase algorithm using the phase algorithm with coherence based kicks 3 Combined algorithm switches between 1 and 2 based on coherence and SNR 4 Group Delay algorithm which is similar to 2 for use with PRIMA This algorithm only uses the Cophase states but instead of tracking
16. ase when the FTK loop state machine is in LOCK state else the output is frozen ZPDSearch block Type ZPDSearch Code file tacZPDSearchBlock c Parameters lt amplitude gt lt period gt lt offset gt OPD Controller As built Software VLT SPE ESO 15420 4000 ESO Detailed Design 2 30 04 2008 20 of 30 Inputs lt fringeDet gt Outputs lt zpdOffset gt The ZPD search trajectory is applied when the lt fringeDet gt input is zero and frozen else The lt amplitude gt and lt period gt parameters define the search speed i e typically 0 1mm in 10s OPD Controller As built Software VLT SPE ESO 15420 4000 E S O Detailed Design 2 30 04 2008 21 of 30 4 2 Commands 4 2 1 Standard Commands with application specific extended behaviour Command Reply Description STOP Ok Suspend FTK and ZPD search Error 4 2 2 Public Commands Command Parameters Reply Description SETFSEN lt sensor gt Ok Identifies which fringe sensor is providing FTK signals If NONE all DL Error control blocks are disabled MIDI or VINCI will enable the INS part of the algorithm where the OPDC propagates the instrument signals directly to the DL possibly changing the sign of the DL offset to cope with geometrical characteristics of the interferometer FNT CH1 FNT CH2 or FNT BOTH will enables one or both FINITO interferometer channels FSU A and FSU B are enabling the PRIMA FSU channel SETDLN lt inputCh gt Ok Ident
17. ce of a LSF software device The background monitoring is handled by an instance of a LSF task device The real time algorithm is exploiting TAC application and its library of function blocks OPD Controller As built Software VLT SPE ESO 15420 4000 E S O Detailed Design 2 30 04 2008 14 of 30 3 2 2 Support Packages The application makes extensive use of the following support packages to implement the standard LCU behaviour and the RT detection algorithm Package Description Name LCU Common Software lec LCU Server Framework Isf Tools for Advanced Control tac RMN Data Interface rmac RFN Data Interface rmacrfm Real time Display rtdscope 3 2 3 CMM Modules This application encompasses the following CMM modules opdc This module contains the complete set of files that compose this application software Application specific software code command handlers and TAC function blocks Online database classes files Online database configuration files both for the application and TAC branches Command definition and interface tables CDT and CIT files TAC algorithm configuration file VLT SPE ESO 15420 4000 This module shall be used to document the historical development of this document At least all drafts preparations and releases which are referenced in any other documents shall be archived as an own version within this module OPD Controller As built Software l VLT SPE ESO 15420 4000 ESO Detailed Design 2 30 04
18. daptive algorithm Detailed information on the adaptive algorithm is found in AD 07 The disturbance model can be used to drive the piezoelectric actuator of the DL to attenuate the harmonic disturbance beyond the rejection bandwidth of the FTK loop OPD Controller As built Software VLT SPE ESO 15420 4000 E S O Detailed Design 2 30 04 2008 19 of 30 4 1 5 TAC Specific Function Block The previous algorithm identifies application specific one TAC function blocks to be designed in the scope of this software the definition of the chopping sequence the FTK and the ZPD search trajectory The other blocks are part of the standard TAC function block library The code of the application specific TAC function blocks was first generated using tacCreateBlock tool ChopSynchro block Type ChopSynchro Code file tacChopSynchroBlock c Parameters lt start gt lt stop gt lt period gt lt dutyCycle gt lt guide gt Inputs None Outputs lt skyOrTarget gt The block outputs a signal that is equal to one when the telescope is expected to point to the target and zero if the telescope is expected to point to the sky FTAlgo block Type FTAlgo Code file tacFTAlgoBlock c Parameters lt numer gt 1 9 lt denom gt 1 9 lt detLevel gt lt openLevel gt lt closeLevel gt lt timeout gt Inputs lt SNR gt lt phase gt lt coherence gt Outputs lt ftkOffset gt The specified digital transfer function is applied to the input ph
19. ecision U Delay Line Fringe Tracking Local Control Unit LCU Common Software LCU Server Framework on C3 Laboratory Input Channel Input Output 5 ABE EE zile Interrupt Service Routine Optical Path Difference OPD Controller OPD Monitor Power PC Reference Document Reflective Memory Network Reflective Memory Network 2nd generation Si Root Mean Square Lei Real Time RT Controller Signal to Noise Ratio a nln m Software Reguirement gt a Tools for Advanced Control Time Interface Module fond ke Universal Time Coordinated lt Very Large Telescope VLT Interferometer Vibration Tracking Zero Path Difference lt S S OPD Controller As built Software VLT SPE ESO 15420 4000 E S O Detailed Design 2 30 04 2008 9 of 30 2 Functional Specification 2 1 Overview Fringe motion happens with earth rotation and any type of disturbance The latter is not predictable needs to be measured and compensated to minimize the residual fringe motion seen by the VLTI instruments it is the purpose of the VLTI Fringe Tracking Facility The facility currently encompasses one fringe sensor i e FINITO or PRIMA a set of Delay Lines DL and one dynamic compensator i e the OPD Controller OPDC The LCU associated to the previous components are all interconnected by means of a fast communication link featuring real time capabilities 1 e the V
20. ent chopping guiding mode e The telescope points by default to the target and M2 periodically offsets to the sky The target light is propagated to the VLTI when M2 is in its center position e The telescope points by default to the sky and M2 periodically offsets onto the target The target light is propagated to the VLTI when M2 is in its offset position The respect of the chopping cycle is guaranteed provided e The start time is an exact UTC second e The chopping period and duty cycle yield target sky time slices that are exact multiples of the OPDC real time sampling period 2 2 Software Requirements The main software requirements SR are Reference Reguirement SR 1 Propagate instrument fringe searching centering offset to the interferometer tracking arm SR 2 Provide VLTI with FTK capability with FINITO PRIMA sensor SR 3 Synchronize FTK facility with telescope chopping cycle SR 4 Publish fringe offset with respect to the blind trajectory by means of DEL FRINGE OFFSET ops log keyword SR 5 Provide FTK with VTK capability OPD Controller As built Software VLT SPE ESO 15420 4000 E S O Detailed Design 2 30 04 2008 11 of 30 2 3 Constraints and Performance The main constraints and performance requirements associated with this software are Dependency Constr 1 N A Provide a VLT standard interface to the outside world Command interpreter Online database Access Error reporting etc Constr 2
21. ention 10 2 1 2 Chopping 10 2 2 Software Requirements 10 2 3 Constraints and Performance 11 2 4 Design Decisions 11 3 ARCHITECTURE OVERVIEW 12 3 1 Hardware 12 3 2 Software 12 32 Application Package 12 3 2 2 Support Packages 14 3 2 3 CMM Modules 14 4 DESIGN DESCRIPTION 15 4 1 TAC Real Time Algorithm 15 4 1 1 TAC Algorithm Structure 15 4 1 2 Fringe Tracking with an Instrument Only i e VINCI or MIDI 16 4 1 3 Fringe Tracking with FINITO or PRIMA incl ZPD Search 16 4 1 4 Vibration Tracking 18 4 1 5 TAC Specific Function Block 19 4 2 Commands 21 4 2 1 Standard Commands with application specific extended behaviour 21 4 2 2 Public Commands 21 4 2 3 Maintenance Commands 21 4 2 4 Test Commands 21 4 3 Online Database 22 4 3 1 Control Branch 22 4 3 2 Configuration Branch 22 4 3 3 Data Branch 22 OPD Controller As built Software ES O Detailed Design 5 APPENDIX 5 1 CDT and CIT files 5 1 1 opdcPublic cdt 5 1 2 opdcTest cdt 5 1 3 opdcSoftDev cit 5 2 Online Database Description Files 5 2 1 opdeDB CONFIG class 5 2 2 opdcDB_DATA class VLT SPE ESO 15420 4000 2 30 04 2008 4 of 30 24 24 24 26 26 27 27 28 OPD Controller As built Software VLT SPE ESO 15420 4000 ESO Detailed Design 2 30 04 2008 5 of 30 TABLE OF FIGURES Figure 1 Schematic Layout of the Fringe Tracking Facility using FINITO ee 9 Figure 2 ORDC LCU Hardware LEE 12 Figure 3 TAC Algorithm Schematic 1 DL 1 FTK channel on 1
22. familiar with VLT software standards 1 3 Applicable Documents The following documents of the issue shown if specified form part of this manual to the extent specified herein In the event of conflict between this document and those referenced the content of this document shall be considered as a superseding requirement unless explicitly stated otherwise herein Document Number Issue Software 2 2 1 1 AD 04 LT MAN ESO 17210 2970 D AD 5 ___ VET MAN BSO 17210 3505 __ AD 06 T SPE ESO 15400 1954 09 11 1999 ICD between VLTI Fast Link and DL OPDC FSU and Instruments AD 07 Adaptive RLS Vibration Cancellation Algorithm OPD Controller As built Software VLT SPE ESO 15420 4000 E S O Detailed Design 2 30 04 2008 8 of 30 1 4 Reference Documents The following documents contain additional information that can be useful to the reader Reference Document Number eene _ Date RD 01 VLT SPE ESO 15430 2790 I 31 08 2006 FINITO Detection Algorithm As built Control Software Detailed Design RD 02 OPD Monitor As built Software Detailed Design 1 5 Acronyms This document employs several abbreviations and acronyms to refer concisely to an item after it has been introduced The following list is aimed to help the reader in recalling the extended meaning of each short expression Meaning Applicable Document Astronomical Detector Unit e c Central Processing Unit Design D
23. ifies the DL and sign for the selected fringe sensor The lt inputCh gt lt trkDL gt Error parameter is used to compute the sign of the OPD offset the lt sign gt lt sign gt parameter is optional the lt inputCh gt provides enough information to compute it STRTCHP lt atTime gt lt time gt Identifies the start time cycle characteristics i e period duty cycle and lt period gt telescope guiding window and stop time of the telescope chopping sequence lt ratio gt This information is used to pause resume FTK when the telescope is pointing lt guide gt to the sky star STOPCHP lt atTime gt lt time gt STRIFTK None Ok Start and stop FTK The sequence is to start ZPD search trajectory with Error STRTFTK the ZPD offset freezes when fringes are detected and FTK loop is STOB None Ok closed When fringes disappear FTK loop is paused and ZPD search resumes Error 4 2 3 Maintenance Commands No application specific maintenance command is identified in the scope of this design 4 2 4 Test Commands Command Parameters Reply Description STRTVTK None Ok Start and stop VTK The frequencies should be listed in a file named Error opdcVTKFreqList tbl in the LCU environment directory STOPVTK None Ok Error SETFMOD lt mode gt Ok Used to switch between AUTOTEST AUTOCOLL and SCIENTIFIC modes Error The gain of the FTK control loop is set to zero for AUTOTEST to 0 5 for for AUTOCOLL and 1 for SCIENTIFIC This functio
24. ilt Software VLT SPE ESO 15420 4000 E S O Detailed Design 2 30 04 2008 10 of 30 2 1 1 About OPD Sign Convention FINITO PRIMA or the VLTI instruments are providing a fringe position error signal the sign of which depends on how the beams are routed in the laboratory i e the OPD provided by the instrument FINITO is defined as the OPL of the beam propagating in the laboratory closest to the tunnel minus the OPL of the other beam E g if we consider the case of UT1 DL1 IC1 and UT2 DL2 IC3 feeding MIDI instrument the OPD computed by MIDI should be OPL UT1 OPL UT2 if the reference DL is DLI the centering offset is applied to DL2 OPL position with the same sign positive OPD means the OPL of UT1 beam is greater than the one of UT2 the fringes are centered by increasing DL2 OPL hence the positive sign if for operational reasons the reference DL is DL2 the same centering offset should be applied to DL1 with opposite sign The OPDC provides a mechanism to change the sign of the fringe centering offset depending on the interferometer configuration 2 1 2 Chopping An instrument like MIDI requires chopping to measure the flux of the scientific target A mode of MIDI considers acquiring fringes with parallel photometry Therefore the telescope might be chopping while FTK The OPDC must suspend the FTK loop when the telescopes are pointing to the sky and resume it when pointing to the target The telescopes can operate in two differ
25. n allows testing FTK without having to modify default control parameters OPD Controller As built Software VLT SPE ESO 15420 4000 E S O Detailed Design 2 30 04 2008 22 of 30 4 3 Online Database The online database structure is directly inherited from LSF with the extensions described below 4 3 1 Control Branch No application specific extension to the LSF control branch is forseen in the scope if this application software Refer to AD 03 for a description of the control database branch e g the background monitoring task scheduling period 4 3 2 Configuration Branch The configuration branch will at least gather the following configuration attributes for each fringe sensor channel i e FNT_CH1 and ENT CH2 Point Attribute Type Description zpd sweep Double ZPD search trajectory parameters The offset is going up to the sweep amplitude mya P Double value in the specified period and then changes sign zpd offset Double fsm det Level Double FTK state machine parameters fsm closeLevel Double fsm openLevel Double fsm timeout Double Set order Double FTK controller discrete transfer function order and coefficients e numer Vector seers denom Vector The database point associated to the instrument configuration contains only a ZPD offset It allows applying a fixed offset to the blind trajectory of the tracking DL e g hold the OPD offset for the night The VTK algorithm is not yet
26. o oko oko oko oko oko ok ok kok kok kok kok kok kok kok kok I I I I I I I OK E S O VLT project Id opdcPublic cdt v 2 1 2008 02 13 20 01 12 vltscem Exp who when what bbauvir 2005 10 24 created Specific COMMAND SETDLN SYNONYMS opdcSoftDevSetTrackingDelayLine FORMAT A PARAMETERS PAR_NAME inputCh PAR_TYPE INTEGER PAR RANGE ENUM 1 3 5 7 PAR DEF VAL 1 PAR NAME dlId PAR TYPE INTEGER PAR RANGE INTERVAL MIN 1 MAX 6 PAR DEF VAL PAR NAME sign PAR TYPE INTEGER PAR RANGE ENUM 1 1 PAR DEF VAL 1 REPLY FORMAT A HELP TEXT Set tracking DL information COMMAND SETFSEN SYNONYMS opdcSoftDevSetFringeSensor FORMAT A PARAMETERS PAR NAME sensor PAR TYPE STRING PAR RANGE ENUM NONE VINCI MIDI FINITO_CH1 FINITO CH2 FINITO BOTH FSUA FSUB MET PAR DEF VAL VINCI REPLY FORMAT A HELP TEXT Set name of currently used fringe sensor G COMMAND SETFMOD SYNONYMS opdcSoftDevSetFTKMode FORMAT A PARAMETERS PAR NAM tri ll mode OPD Controller As built Software VLT SPE ESO 15420 4000 E S O Detailed Design 2 30 04 2008 25 of 30 PAR_TYPE STRING PAR RANGE ENUM NONE AUTOTEST AUTOCOLL SCIENTIF
27. ware VLT SPE ESO 15420 4000 E S O Detailed Design 2 30 04 2008 12 of 30 3 Architecture Overview 3 1 Hardware The following LCU architecture has been selected for this application 2 Motorola PPC CPU boards used in a Master Slave configuration 1 ESO Time Interface Module TIM board 1 VMIC VMIVME 5576 Reflective Memory Network RMN board 1 VMIC VMIPMC 5565 Reflective Memory Network RFM board This is a daughter card piggybacked on the Slave PPC CPU board MVME2604 MYME2604 VMIVME5576 Figure 2 OPDC LCU Hardware structure 3 2 Software 3 2 1 Application Package This software is responsible for the control of the OPDC It encompasses the following components e A command interface based on CCS message system and on a command interpreter running on the first CPU board of the LCU e A public database providing status and signals information e A real time process running on the second CPU board e A graphical engineering user interface Compliancy with AD 01 is ensured by the use of LSF to implement standard behaviour and to generate part of the application specific code command handling routines and database structure The application software was generated using sfConfig tool LSF configuration file can be found in the appendix OPD Controller As built Software VLT SPE ESO 15420 4000 ESO Detailed Design 2 30 04 2008 13 of 30 Interaction with the real time algorithm is done through an instan
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