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1. FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 E S O Software Detailed Design 2 31 08 2006 8 of 31 1 4 Reference Documents The following documents contain additional information that can be useful to the reader Reference Document Number Issue Date ride RD vrr sPE oRr 15430 0003 10 2370372001 RD 04 VLT SPE ESO 15430 2790 31 08 2006 FINITO Detection Algorithm As built Control 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 po Design Decision LSE TED Zero Optical Path Difference FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 E S O Software Detailed Design 2 31 08 2006 9 of 31 2 Functional Specification 2 1 Overview An overall description of FINITO can be found in RD401 The Alignment and Compensation Unit ACU provides control over three active units one for each FINITO beam Each unit is constituted by a flat mirror mounted on a piezoelectric platform providing tip and tilt action This platform rests on a motorized translation stage in a way that the reflected light beam is parallel to the translation axis when the piezoelectric platform is in its center position The ACU function is multiple Initial a2. FUNCTION FUNCTION FUNCTION FUNCTION FUNCTION FUNCTION FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 E S O Software Detailed Design 2 31 08 2006 29 of 31 6 2 Online Database Description files 6 2 1 fntttpDB DATA class St kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk kk E S O VLT project Va NL Id fntttpDB DATA class v 1 29 2006 06 28 17 21 01 vltsccm Exp LEE who when what d ee EE et ZE EE EE pduhoux 2000 04 06 created a 8 include IsfDB DATA class include tacDB DATA class CLASS BASE CLASS fntttpDB DATA IFG BEGIN ATTRIBUTE int32 status 0 ATTRIBUTE double thetaX O0 ATTRIBUTE double thetaY O0 END CLASS BASE CLASS fntttpDB DATA BTK BEGIN ATTRIBUTE int32 status 0 ATTRIBUTE double thetaX O0 ATTRIBUTE double thetaY O0 ATTRIBUTE double error 0 END CLASS BASE CLASS fntttpDB DATA TTP BEGIN ATTRIBUTE double thetaX O0 ATTRIBUTE double thetaY O0 ATTRIBUTE fntttpDB DATA IFG ifg ATTRIBUTE fntttpDB DATA BTK btk ifdef MAKE VXWORKS ATTRIBUTE tacDB MONIT SIGNAL monitor BEGIN ATTRIBUTE Vector name tacMAX DATA NUMBER bytes64 BEGI Value TXTTP Setpoint mRad TYTTP Setpoint mRad TXTTP BTK offset mRad TYTTP BTK offset mRad Average flux ADU TXTTP BTK error mRad TYTTP BTK erro
3. fntttpMaintenance cdt 6 1 3 fntttpTest cdt 6 1 4 fntttpSoftDev cit 6 2 Online Database Description files 6 2 1 fntttpDB DATA class 6 2 2 fntttpDB CONFIG class 21 21 21 21 21 23 23 23 25 26 27 29 29 30 Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 E S O Software Detailed Design 2 31 08 2006 5 of 31 TABLE OF FIGURES SCHWEL Hard Ware sine Ee budet da vitem tt act 12 TAC Algorithm schematic ER EE 15 EE e 16 Principle of synchronous demodulation June aede pert ee in 16 Alignment using synchronous demodulation enn 17 produnt HR 18 Conversion into equipment characteristics a a etes eeu tn ehe e pap nh ete eio eee EE 18 FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 E S O Software Detailed Design 2 31 08 2006 6 of 31 This page has been left intentionally blank FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 E S O Software Detailed Design 31 08 2006 7 of 31 1 Introduction 1 1 Purpose This document aims to present the design of FINITO Tip Tilt Platform Control Software that is part of FINITO Alignment and Compensation Unit It is intended to be used as an input for the design of FINITO Workstation Software as well as a manual for user operation 1 2 Scope This document shall first shortly describe FINITO Alignment and Compensation Unit It will then present the require
4. fntttpSoftDevStartBeamTracking FORMAT A PARAMETERS PAR NAME platformId PAR TYPE INTEGER PAR RANGE INTERVAL MIN 0 MAX 2 PAR DEF VAL 0 REPLY FORMAT A HELP TEXT Start beam tracking function The function returns when the beam is acquired It is interrupted by STOPBTK command COMMAND STOPBTK SYNONYMS fntttpSoftDevStopBeamTracking FORMAT A PARAMETERS PAR NAME platformId PAR TYPE INTEGER PAR RANGE INTERVAL MIN 0 MAX 2 PAR DEF VAL 0 REPLY FORMAT A HELP TEXT S H top beam tracking function FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 E S O Software Detailed Design 2 31 08 2006 25 of 31 6 1 2 fntttpMaintenance cdt LS EEE K K K kk kk kk kk kk Ck kk Ck Ck Ck Ck Ck oko kk oko E S 0 VLT project Id fntttpMaintenance cdt v 1 29 2006 06 28 17 21 01 vltsccm Exp bbauvir 2001 10 25 created Specific COMMAND ENAIFG SYNONYMS fntttpSoftDevEnableIRISGuiding FORMAT A PARAMETERS PAR NAME platformId PAR TYPE INTEGER PAR RANGE INTERVAL MIN 0 MAX 2 PAR DEF VAL 0 REPLY FORMAT A HELP TEXT Enable IRIS guiding for the specified Tip Tilt Platform COMMAND DISIFG SYNONYMS fntttpSoftDevDisableIRISGuiding FORMAT A PARAMETERS PAR NAME p
5. 1 29 2006 06 28 17 21 01 vltsccm Exp bbauvir 2001 10 25 created COMMAND SETTILT SYNONYMS fntttpSoftDevSetTiltPosition E platformId TYPE INTEGER PAR RANGE INTERVAL MIN 0 MAX 2 PAR NAME thetaX PAR TYPE z REAL PAR RANGE INTERVAL MIN 0 001 MAX 0 001 PAR DEF VAL 0 PAR NA PAR TYP PAR RANGE INTERVAL MIN 0 001 MAX 0 001 PAR DEF VAL 0 REPLY FORMAT A HELP TEXT Set Tip Tilt Platform angles rad COMMAND GETTILT SYNONYMS fntttpSoftDevGetTiltPosition FORMAT A PARAMETERS PAR NAME platformId PAR TYPE INTEGER PAR RANGE INTERVAL MIN 0 MAX 2 PAR DEF VAL 0 REPLY FORMAT A REPLY PARAMETERS PAR NAME thetaX PAR TYPE REAL PAR NAME thetaY PAR TYPE REAL HELP TEXT FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 Software Detailed Design 2 31 08 2006 24 of 31 Retrieves Tip Tilt Platform angles rad G COMMAND CENTER SYNONYMS fntttpSoftDevCenterPosition FORMAT A PARAMETERS PAR NAME platformId PAR TYPE INTEGER PAR RANGE INTERVAL MIN 0 MAX 2 PAR DEF VAL 0 REPLY FORMAT A HELP TEXT Center the TTP to the middle of the angular range COMMAND STRTBTK SYNONYMS
6. TTP TTPO ATTRIBUTE fntttpDB CFG TTP TTP1 ATTRIBUTE fntttpDB CFG TTP TTP2 END END OF FILE FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 E S O Software Detailed Design 2 31 08 2006 31 of 31 oOo
7. and vertical references Fix the offset parameters and send the TTP X axis to Imrad at software level with the following command prompt gt msgSend LCUENV fntttpServer SETTILT 0 0 001 0 0 Modify the rotation matrix angle in order for the light spot to move along the horizontal reference axis prompt gt msgSend LCUENV tacServer MODBLCK TTPO Convert Rotation angle Change the slope with the following command until the TTP is properly deviating the incoming beam by le 3 rad prompt gt msgSend LCUENV tacServer MODBLCK TTPO Convert TX mrad2V lt slopeX gt lt offsetX gt Send the TTP Y axis to 1 mrad at software level prompt msgSend LCUENV fntttpServer SETTILT 0 0 0 0 001 Verify that the rotation angle is correct the light spot should have moved along the vertical reference axis Repeat for the Y axis prompt gt msgSend LCUENV tacServer MODBLCK TTPO Convert TY mrad2V lt slopeY gt lt offsetY gt The new parameters may be saved by generating a new TAC configuration file prompt gt msgSend LCUENV tacServer REPORT fntttp tac It is essential that the measured parameters be archived in the fntttp CMM module FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 E S O Software Detailed Design 2 31 08 2006 23 of 31 6 Appendix 6 1 CDT and CIT files 6 1 1 fntttpPublic cdt N BR RK IK kk kk kk kk kk Ck Ck Ck Ck Ck Ck Ck Ck kk kk E S 0 VLT project Q 4 Id fntttpPublic cdt v
8. applied Starts the circular modulation with the specified lt amplitude gt Closes the beam centering loop by setting the integrator gain to its nominal value e Attaches a callback to the associated data Monitor block to measure the average flux periodically update the flux normalization gain and the estimated centering error When the centering error goes below a threshold or has not yet reached the threshold after a configurable time the centering loop is disabled by setting the modulation amplitude and integrator gain to zero STOPBTK lt ttpld gt Ok Stops an ongoing beam centering procedure Error 4 2 3 Maintenance Commands Command Parameters Reply Description ENAIFG lt ttpld gt Ok Enables IFG i e the fast control of the TTP from the guider error vector for the Error specified TTP This is achieved by setting the lt pixel2mRad gt gain parameter to its nominal value DISIFG lt ttpld gt Ok Disables IFG for the specified TTP This is achieved by setting the lt pixel2mRad gt Error gain parameter to zero GETIFG lt ttpld gt lt status gt Returns the status boolean of IFG function ENABTK lt ttpld gt Ok Enables BTK i e automatic beam centering for the specified TTP This is Error achieved by starting the circular modulation setting the modulation lt amplitude gt parameter and integrator lt gain gt to their nominal value DISBTK lt ttpld gt Ok Disables BTK for the specified TTP This
9. E ESO 15430 2786 E S O Software Detailed Design 2 31 08 2006 3 of 31 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 Optical Alignment 9 2 1 2 Astronomical beam injection 9 2 1 3 Atmospheric Dispersion Compensation 9 2 1 4 OPD offsets while fringe tracking 10 2 2 Software Requirements 10 2 3 Constraints and Performance 10 2 4 Design Decisions 11 3 ARCHITECTURE OVERVIEW 12 3 1 Hardware 12 3 2 Software 13 3 2 1 Application Package 13 3 2 2 Support Packages 13 3 2 3 CMM Modules 13 4 DESIGN DESCRIPTION 15 4 TAC Control Algorithm 15 4 1 Absolute setpoint 16 4 1 2 Beam tracking 16 4 1 3 Fast guiding 17 4 1 4 Conversion into the equipment reference system 18 4 2 Commands 18 4 2 1 Standard Commands with application specific extended behaviour 18 4 2 2 Public Commands 18 4 2 3 Maintenance Commands 19 4 2 4 Test Commands 19 4 3 Online Database 20 4 3 1 Control Branch 20 4 3 2 Configuration Branch 20 4 3 3 Data Branch 20 FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 E S O Software Detailed Design 2 31 08 2006 4 of 31 5 USER MANUAL 5 1 Installing the software 5 2 Real time display and engineering graphical user interface 5 3 Configuring the software 5 3 1 Conversion to equipment reference system 6 APPENDIX 6 1 CDT and CIT files 6 1 1 fntttpPublic cdt 6 1 2
10. ESO 15430 2786 E S O Software Detailed Design 2 31 08 2006 21 of 31 5 User Manual 5 1 Installing the Software The steps to install the fntttp application software on a LCU and workstation environment may be extracted from in the environment templates of the software test suite prompt gt cmmCopy fntttp prompt gt find fntttp name src xargs I DIR gt sh c cd DIR amp amp make all install prompt gt cd fntttp lcu test ENVIRONMENTS prompt gt export WSENV lt wsEnv gt prompt gt export LCUENV lt lcuEnv gt prompt gt vccEnvCreate e WSENV s wsTat prompt gt vccEnvCreate e LCUENV t LCU h HOST d vltdata ENVIRONMENTS LCUENV X gt s lcuTat w WSENV prompt gt vccEnvStart e WSENV prompt gt lecBoot LCUENV 5 2 Real time Display and Engineering Graphical User Interface The fntttp application provides an engineering graphical user interface and a real time display panel exploiting rtdscope application The two panels are started with the following shell commands prompt gt fntttpgui amp prompt gt rtdscopeGui amp The update of the real time display is started putting the two applications ONLINE prompt gt msgSend LCUENV fntttpServer ONLINE prompt gt msgSend LCUENV rtdscopeServer ONLINE The real time display shows by default TTPO control signals Change the TTP the real time display is connected to by prompt gt msgSend LCUENV rtdscopeServer STANDBY prom
11. EUROPEAN SOUTHERN OBSERVATORY Organisation Europ enne pour des Recherches Astronomiques dans l H misph re Austral Europ ische Organisation f r astronomische Forschung in der s dlichen Hemisph re ESO Technical VLT PROGRAMME ACCEPTED BY Archive 10 10 2006 VERY LARGE TELESCOPE FINITO Tip Tilt Platform Control Software Detailed Design Doc No VLT SPE ESO 15430 2786 Issue 2 Date 31 08 2006 Prepared Bertrand Bauvir Henri Bonnet Name Signature Approved Anders Wallander Markus Sch ller VILLA Name Date a d Released Andreas Kaufer als a ran Name Date Signature VLT PROGRAMME TELEPHONE 089 3 20 06 0 FAX 089 3 20 06 514 FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 Software Detailed Design 2 31 08 2006 2 of 31 CHANGE RECORD SECTION PAGE REASON INITIATION AFFECTED DOCUMENTS REMARKS l prep 1 11 08 2002 All First draft l prep 2 16 10 2002 All Second draft prepared for review l prep 3 14 01 2003 All Third draft after review 1 25 01 2003 All First release 2 prep 1 31 07 2006 2 1 2 2 amp 2 4 Add requirements related to IRIS Fast Guiding and Flux Tracking Po 41 amp 42 Enhance TAC algorithm structure and add new commands Flux tracking stops when converged Modify CENTER command FTK renamed BTK Add dedicated point for configuration 2 308206 Second release after review Loca iM FINITO Tip Tilt Platform Control VLT SP
12. EXT Retrieves Tip Tilt Platform Beam Tracking status bool 6 1 3 fntttpTest cdt J RRR RK RK kk kk kk kk kk kk kkk kkk kok kok Ck ok kok k kok kk kkk 2 2 2 22 kok kok kok 2 2 kok kok kok 22 2 2 2 2 22 20 E S O VLT project X X Lu Q 4 Id fntttpTest cdt v 1 29 2006 06 28 17 21 01 vltsccm Exp bbauvir 2001 10 25 created Specific COMMAND ENAMOD SYNONYMS fntttpSoftDevEnableModulation FORMAT A PARAMETERS PAR NAME platformId PAR TYPE INTEGER PAR RANGE INTERVAL MIN 0 MAX 2 PAR DEF VAL 0 DO EPLY FORMAT A FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 E S O Software Detailed Design 2 31 08 2006 27 of 31 HELP TEXT Enable circular modulation for the specified Tip Tilt Platform COMMAND DISMOD SYNONYMS fntttpSoftDevDisableModulation FORMAT A PARAMETERS PAR NAME platformId PAR TYPE INTEGER PAR RANGE INTERVAL MIN 0 MAX 2 PAR DEF VAL 0 REPLY FORMAT A HELP TEXT Disable circular modulation for the specified Tip Tilt Platform H COMMAND GETMOD SYNONYMS fntttpSoftDevGetModulation FORMAT A PARAMETERS PAR NAME platformId PAR TYPE INTEGER PAR RANGE INTERVAL MIN 0 MAX 2 PAR DEF VAL 0 REPLY FORMAT A HELP TEXT Retrieves Tip Tilt Platform modulation status
13. TXTTP Notch TXTTP TXTTP Gain TXTTP A Error Integrator k K gt Es Modulation TXTTP Amplitude we num s 1 x a 2 5 ES stwuc dents gt gt gt Z Fi e i P NM TYTTP mRad Phase Shift TYTTP Mixer TYTTP LowP ass TYTTP Notch TYTTP TYTTP Gain TYTTP of pi 2 Error Integrator K TYTTP Amplitude E Threshold Monitor Figure 5 Alignment using synchronous demodulation The notch filters are used to reject further i e further than the rejection provided by the low pass filters the circular modulation signal from the integrator input The centering error is estimated from the individual tip tilt error signals and passed into a comparator function The signal monitoring part is used to report to the application server the flux and state converged or not of the centering loop The server is then capable of measuring at a slow rate the average flux for flux normalization purpose and automatically stopping modulation automatically when the estimated centering error is sufficiently small the function appearing in green on the previous schematic may be executed in the data monitoring callback as it is not essential to the real time control ofthe TTP The configurable parameters are the modulation lt amplitude gt integrator lt gain gt and comparator lt threshold gt The frequency is not configurable a priori but shall be selected within vibration free frequency regions 4 1 3 Fast Guiding An open loop gui
14. TYTP1 axis control Channel 3 10V TXTP2 axis control Channel 4 10V TYTP2 axis control Channelf5 10V FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 E S O Software Detailed Design 2 31 08 2006 13 of 31 3 2 Software 3 2 1 Application Package The software is responsible for the control of the TTP subsystem of FINITO It encompasses the following components A command interface based on CCS message system and on a command interpreter running on the CPU board of the ACU LCU A public database providing status and signals information Anengineering graphical user interface for test or maintenance purposes 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 The application software architecture is described in AD 06 Interaction with the TTP is done through an instance of a LSF software device The real time control algorithm is exploiting TAC application and its library of function blocks 3 2 2 Support Packages The application makes extensive use of the following support packages to implement the standard LCU behaviour and TTP control algorithm and provide the user with an engineering graphical interface Package Description Name LCU Common Software lec LC
15. U Server Framework Isf Tools for Advanced Control tac RMN Data Interface rmac Real Time Plotting Tools rtdscope 3 2 3 CMM Modules This application encompasses the following CMM modules fntttp This module contains the complete set of files that compose this application software e Application specific software code e Online database classes files e Online database configuration files Command definition and interface tables CDT and CIT files TAC algorithm configuration file Engineering graphical user interface panels FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 E S O Software Detailed Design 2 31 08 2006 14 of 31 VLT SPE ESO 15430 2786 This module shall be used to document the historical development of this document At least all drafts preparations and releases that are referenced in any other documents shall be archived as an own version within this module FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 E S O Software Detailed Design 2 31 08 2006 15 of 31 4 Design Description This section presents the design of the fntttp application software 4 1 TAC Control Algorithm The following diagram represents the TAC algorithm that implements the control of FINITO TTP angular positions The blocks appearing in blue are instantiated three times once for each beam In order to avoid rounding errors lt thetaX gt and lt thetaY gt are expressed in mrad at the level of TAC
16. ad Figure 3 External setpoint 4 1 2 Beam Tracking Accurate centering of the scientific beams onto the FINITO input fibers is achieved by means of synchronous demodulation The principle is to apply a harmonic circular modulation to the TTP the flux measured on the associated photometric channel will feature a component at the modulation frequency if the beam is not centered onto the input fiber the phase of which defines the direction of the de centering x O s e A A A g Z CA TA y IL 2 T uns D E J E A CH A d d S Static tilt 10mas 0 zi tilt mas 50 50 tip mas 0 05 0 15 0 2 ime S 1 x E 17 o 0 8 gt xpi S gas en ir 08 D koj i N 04 0 E 50 302 P static tilt O 0 tilt mas 50 50 tip mas 0 05 0 15 0 2 Ime S Figure 4 Principle of synchronous demodulation FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 E S O Software Detailed Design 2 31 08 2006 17 of 31 Automatic centering is achieved by e g multiplying the normalized ADU flux with the modulation signal extracting its DC component the sign of which defines in which direction is the center of the fiber and the amplitude of which is proportional to the centering error and integrating it to converge to the center of the fiber d 4 a Flux N li ormalize we numfs pm EE re stue dens I TXTTP mRad TXTTP Mixer TXTTP LowP ass
17. algorithm while external interface is defined in radians TIM 2kHz TTPO Scope TTPO Setpoint TTPO BTK Offset TTPO IFG Offset Channels Channels Channel 2 TTPO mRad2V Channel 3 Channel 4 TTPO RMN Channel 5 MP va55 Figure 2 TAC Algorithm schematic one beam It encompasses the following parts A block to configure the TIM board to generate interrupts at 2KHz rate e A block to access the required data on the VMIVME5536 RMN board A block to access the Pentland Systems MPV955 DAC board A data monitoring block to allow real time inspection using rtdscope application or recording in a file the different control signals using TAC record mechanism A set of blocks that provides the user with an interface to define the TTP absolute angular position e A Beam Tracking BTK function to center the scientific beams on the input optical fiber i e maximize the flux injected into FINITO A Fast Guiding IFG function to minimize the beam wander induced by light duct turbulence A function to convert the TTP angular position from laboratory to equipment reference system FINITO Tip Tilt Platform Control ESO Software Detailed Design EE 2 31 08 2006 16 of 31 4 1 1 Absolute Setpoint Two constant blocks provide the user with an interface to define the TTP absolute angular position i e low accuracy alignment TADC offset etc thetax TATTP mRad thetaY TYTTP mR
18. amplifiers with 2V 12V analog input signal 2 2 Software Reguirements The main software requirements SR are extracted from AD 06 and AD 08 Reference Requirement SR 1 Provide angular control over the FINITO TTP platforms SR 2 Provide an automatic procedure to align FINITO with respect to the scientific beams SR 3 Provide a mechanism to drive the TTP from the error vector measured by the VLTI laboratory guider i e IRIS 2 3 Constraints and Performance The main constraints and performance requirements associated with this software are Reference Dependency Constraint Constr 1 N A Provide a VLT standard interface to the outside world Command interpreter Online database Access Error reporting etc Constr 2 SR 3 Minimize the delay between the measurement and application of the guiding error vector measured by IRIS FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 E S O Software Detailed Design 2 31 08 2006 11 of31 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 The TTP angles will be remotely controlled by means of high resolution analog signals DD 3 DD 2 As six analog channels are required the analog interface will be provided by a Pentland Systems MPV955 DAC board DD 4 DD 3 In order to reuse the codin
19. ay arise due to the different optical path along the common air column as well as a different apparent position in the sky associated to differential air refraction An Atmospheric Dispersion Compensation ADC is required to correct these two atmospheric effects FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 E S O Software Detailed Design 2 31 08 2006 10 of 31 2 1 4 OPD Offsets while Fringe Tracking When VLTI is operated in fringe tracking the delay lines are controlled to maintain zero OPD condition among telescope beams as measured by FINITO ADU An instrument may require VLTI to apply an OPD offset between the telescope beams in order i e to center the scientific fringe packet on the instrument detector Such offset is produced by applying the same offset with opposite sign between FINITO beams by means of the TST motion in order to drag the OPD as seen by the instrument to the requested position The purpose of this software is the control of FINITO TTP to provide the transversal optical alignment optimal astronomical beam injection and TADC functions of the ACU The computation of the TADC for the observed target is not part of the scope of this software The TADC requirements can be found in AD 07 and are listed hereafter as a reminder Range lmrad Resolution lt 0 1urad Update rate lt 1Hz The TTP are Physik Instrumente S 330 10 Piezo Tip Tilt operating in closed loop They are delivered with high voltage
20. bool 6 1 4 fntttpSoftDev cit J RR RR RK RK kk kk kk kk Ck Ck Ck kk Ck Ck Ck kkk kok kok kok kkk kkk 2 kok kok kok kok kok kok 2 CK K CK Ck K Ck AK Ck A K E S 0 VLT project Q 4 Id fntttpSoftDev cit v 1 29 2006 06 28 17 21 01 vltsccm Exp pduhoux 2000 07 04 created This file has been generated by a utility 1111111111 DO NOT MANUALLY EDIT THIS FILE J BR RR RK RK kk kk kk kk Ck Ck kk kkk kkk kkk kkk kk kCk kk kCk kCKCkCKCKCKCKCKCKCKCKCAKCKCKCKCKCKCAKCK CK K CK Ck ck ck Ok A k x Lf Specific SETTILT IfntttpSoftDevSetTiltPosition FUNCTION ETTILT IfntttpSoftDevGetTiltPosition FUNCTION ENTER IfntttpSoftDevCenterPosition FUNCTION TRTBTK IfntttpSoftDevStartBeamTracking TASK fntttpBTK 30000 TOPBTK IfntttpSoftDevStopBeamTracking FUNCTION AIFG IfntttpSoftDevSetIRISGuiding FUNCTION DISIFG IfntttpSoftDevSetIRISGuiding FUNCTION Boon FINITO Tip Tilt Platform Control E S O Software Detailed Design VLT SPE ESO 15430 2786 2 31 08 2006 28 of 31 GETIFG IfntttpSoftDevGetIRISGuiding ENABTK IfntttpSoftDevSetBeamTracking D IfntttpSoftDevSetBeamTracking GETBTK IfntttpSoftDevGetBeamTracking D G H un w X AMOD IfntttpSoftDevSetModulation ISMOD IfntttpSoftDevSetModulation ETMOD IfntttpSoftDevGetModulation FUNCTION
21. d then fed to the MPV955 DAC board TXTTP dab TXTTP mech TYTTP ab TYTTP mech TYTTP mRad TYTTP mRad2V TYTTP OY Rotation Figure 7 Conversion into equipment characteristics The configurable parameters are the rotation lt angle gt physical axes are considered orthogonal and conversion factors lt slope gt and offset 4 2 Commands 4 2 1 Standard Commands with application specific extended behaviour Command Description STOP Stops ongoing modulation and beam centering procedures 4 2 2 Public Commands Command Parameters Reply Description SETTILT lt ttpld gt Ok Requests the specified TTP to move to a new angular position lt thetaX gt and lt thetaX gt Error lt thetaY gt are expressed in rad This command modifies the parameters of the lt thetaY gt setpoint constant blocks The command returns when the motion is complete or in case of failure Q ETTILT lt ttpld gt lt thetaX gt Retrieves the current position in rad of the specified TTP lt thetaY gt FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 Software Detailed Design i 2 31 08 2006 19 of 31 CENTER lt ttpld gt Ok Requests the specified TTP to move to the center of the angular range Error STRTBTK lt ttpld gt Ok Requests the specified TTP to center the beam onto the input fiber The command Error returns when the motion is complete or in case of failure The following procedure is
22. ding strategy has been elected The scientific beams are aligned with respect to VLTI reference by means of slow guiding the telescope probe from IRIS imager located in the laboratory FINITO ACU applies a TTP position offset from each measured error vector Eg the slow guiding of the telescope probe will not respond to a 1Hz displacement of the beam around IRIS guiding pixel but FINITO will still require a local compensation to maintain optimal alignment FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 Software Detailed Design i 2 31 08 2006 18 of 31 num s K gt 1 Be TXTTP pixel den a TXTTP mRad TXTTP LowP ass TXTTP Notch TXTTP pixel2mRad num s i Gg TYTTP pixel dents ge TYTTP mRad TYTTP LowP ass TYTTP Notch TYTTP pixel2mRad Figure 6 IRIS fast guiding IRIS error vector is first saturated to avoid driving the TTP during beam acquisition filtered to avoid amplification of high frequencies due to delay and converted from pixel scale into mrad The configurable parameters are the saturation lt thresholds gt and lt pixel2mRad gt conversion factors 4 1 4 Conversion into the Equipment Reference System Each TTP may be misaligned with respect to the vertical and horizontal axes Therefore the angular positions are first passed through a rotation matrix to generate the requested angular position around the TTP physical axes The associated voltage is computed using a linear law an
23. erate the TTP in IFG by default btk gain Double BTK integrator lt gain gt The same parameter is applied to both axes ofthe TTP btk amplitude Double BTK modulation lt amplitude gt The same parameter is applied to both axes of the TTP btk threshold Double BTK convergence criterion btk timeout Double Time after which STRTBTK will return an error if not yet converged The other parameters reguired for the real time control algorithm are not dynamically modified by the software and therefore appear in the TAC algorithm configuration file 4 3 3 Data Branch The data branch will at least gather the following attributes for each TTPO 2 point Point X Attribute Type Description thetaX Double Current absolute position in rad of the TTP X axis thetaY Double Current absolute position in rad of the TTP Y axis ifg thetaX Double Current IFG offset averaged over 1s in rad for the TTP X axis ifg thetaY Double Current IFG offset averaged over 1s in rad for the TTP Y axis ifg status Integer IFG status 0 undefined 1 off and 2 on btk thetaX Double Current BTK offset averaged over 1s in rad for the TTP X axis btk thetaY Double Current BTK offset averaged over 1s in rad for the TTP Y axis btk error Double Estimated BTK centering error averaged over 1s in rad btk status Integer BTK status 0 undefined 1 off and 2 on FINITO Tip Tilt Platform Control VLT SPE
24. g effort conducted for the design of FINITO Fiber Modulator Unit the software will be based on TAC mechanism channel flux from the ADU by means of the VLTI Reflective Memory Network RMN IRIS activity is not synchronized to the TIME bus The TTP real time activity will be triggered by the TIM board and executed at 2kHz in order to minimize communication delay At the time of this design no VLT compliant Vx Works driver was available and LSF did only provide interface to the VLT standard VMIC VMIVME3111 analog IO board FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 E S O Software Detailed Design 2 31 08 2006 12 of 31 3 Architecture Overview 3 1 Hardware The following LCU architecture has been selected for this application e 1 Motorola PPC CPU board e VMIC VMIVMES576 Reflective Memory board 1 ESO Time Interface Module TIM board 1 Pentland Systems MPV955 16 bits resolution Digital to Analog Converter DAC board Translation Stage 1 3 VLTI RMN Tip Tilt ctuator l 3 VMIVMES5536 MAC4INC VMEAG A MVME 2604 Figure 1 ACU LCU Hardware structure The other boards i e motor controller board and amplifier present in the ACU LCU are dedicated to the control of FINITO TST The design assumes the following analog signal interface Signal MPV955 Range TXTPO axis control Channel 0 10V TYTPO axis control Channel l 10V TXTPI axis control Channel 2 10V
25. is achieved by setting the lt amplitude gt Error and integrator lt gain gt parameters to zero GETBTK lt ttpld gt status Returns the status boolean of BTK function 4 2 4 Test Commands Command Parameters Reply Description ENAMOD lt ttpld gt Ok Enables the circular modulation for the specified TTP This is achieved by starting Error the circular modulation setting the modulation lt amplitude gt parameter The integrator lt gain gt parameter is maintained to zero DISMOD lt ttpld gt Ok Disables the circular modulation for the specified TTP This is achieved by setting Error the lt amplitude gt parameter to zero GETMOD lt ttpld gt status Returns the status boolean of modulation function FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 E S O Software Detailed Design 2 31 08 2006 20 of 31 4 3 Online Database The online database structure is directly inherited from LSF with the extensions described below 4 3 1 Control Branch No extension to the LSF control branch is foreseen in the scope of this application software 4 3 2 Configuration Branch The configuration branch will contain the following application specific configuration attributes for each TTPO 2 point Point X Attribute Type Description SIEG pixel2rad Double IFG conversion factor from IRIS pixel scale to radian Sg saturation Double IFG saturation threshold in pixel scale ifg enable Boolean Set to op
26. latformId PAR TYPE INTEGER PAR RANGE INTERVAL MIN 0 MAX 2 PAR DEF VAL 0 REPLY FORMAT A HELP TEXT Disable IRIS guiding for the specified Tip Tilt Platform H COMMAND GETIFG SYNONYMS fntttpSoftDevGetIRISGuiding FORMAT A PARAMETERS PAR NAME platformId PAR TYPE INTEGER PAR RANGE INTERVAL MIN 0 MAX 2 PAR DEF VAL 0 REPLY FORMAT A HELP TEXT Retrieves Tip Tilt Platform IFG status bool COMMAND ENABTK SYNONYMS fntttpSoftDevEnableBeamTracking FORMAT A PARAMETERS PAR NAME platformId PAR TYPE INTEGER PAR RANGE INTERVAL MIN 0 MAX 2 PAR DEF VAL 0 FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 E S O Software Detailed Design 2 31 08 2006 26 of 31 REPLY FORMAT A HELP TEXT H Enable Beam Tracking for the specified Tip Tilt Platform COMMAND DISBTK SYNONYMS fntttpSoftDevDisableBeamTracking FORMAT A PARAMETERS PAR NAME platformId PAR TYPE INTEGER PAR RANGE INTERVAL MIN 0 MAX 2 PAR DEF VAL 0 REPLY FORMAT A HELP TEXT Disable Beam Tracking for the specified Tip Tilt Platform H COMMAND GETBTK SYNONYMS fntttpSoftDevGetBeamTracking FORMAT A PARAMETERS PAR NAME platformId PAR TYPE INTEGER PAR RANGE INTERVAL MIN 0 MAX 2 PAR DEF VAL 0 REPLY FORMAT A HELP T
27. lignment and optical path balancing of the telescope beams on FINITO e Optimization of the astronomical beam injection Compensation of the atmospheric effects due to the observing geometry Application of OPD offsets required by external instruments while fringe tracking These four functions are shortly presented below A complete description can be found in AD 06 2 1 1 Optical Alignment The first function of the ACU is the alignment of FINITO with respect to VLTI beams The Tip Tilt Platform TTP is moved in order to maximize the photon flux on the corresponding Astronomical Detector Unit ADU photometric channel The Translation Stage TST is moved to have fringes at internal Zero Optical Path Difference ZOPD 2 1 2 Astronomical Beam Injection The second function of the ACU is the stabilization of the scientific beams on the FINITO input fiber real time stabilization of the scientific beams is required to minimize the effect of tip tilt induced by turbulence in the light duct or tunnel on FINITO operation FINITO requires an external imager to provide it with fast tip tilt error information 2 1 3 Atmospheric Dispersion Compensation The third function of the ACU is to perform Transversal and Longitudinal Atmospheric Dispersion Compensation TADC and LADC respectively In general the scientific instrument may operate at a different wavelength than FINITO Therefore a mismatch between the respective positions of ZOPD m
28. ments and constraints associated to this software component Some design decisions are then issued from these requirements The LCC libraries messaging system and database are documented in AD 02 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 design description section of this document mainly focuses on the application specific extensions brought to LSF and the TAC based real time computation required to provide the specified functionality In addition the reader should be 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 Reference Document Number Issue Date Tile AD 01 VLT MAN ESO 17210 0667 ES 03 12 1996 Guidelines for the cu OM of VLT Application Software AD 02 VLT MAN SBI 17210 0001 3 5 20 10 1999 LCU Common Software User Manual AD 03 05 07 2002 LCU Server Framework User Manual AD 08 VLT SPE ESO 15430 4021 1 31 08 2006 FINITO Beam Acquisition and Stabilization Technical Specification
29. pt gt dbWrite LCUENV rtdscope control misccfg block TTP2 RTD Scope prompt gt msgSend LCUENV rtdscopeServer ONLINE 5 3 Configuring the Software 5 3 1 Conversion to Equipment Reference System The software is configured assuming that 10V on the output of the MPV955 board corresponds to lmrad The conversion parameters are part of the TAC configuration file and may be changed to fit the actual hardware reality The procedure assumes that an artificial light source is fed to FINITO and that the angular displacement of the beam axis is monitored using a sighting telescope The translation blocks apply the standard linear formula V slope mrad offset The following example concerns TTPO The best way to determine the actual slope and offset parameters is first to tune the voltage offset FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 E S O Software Detailed Design 2 31 08 2006 22 of 31 Center the TTP at software level with the following commands prompt gt msgSend LCUENV fntttpServer ONLINE prompt gt msgSend LCUENV fntttpServer CENTER 0 Then change the offset with the following commands until the TTP is properly centered on the X and Y axes prompt gt msgSend LCUENV tacServer MODBLCK TTPO Convert TX mrad2V 0 0 lt offsetX gt prompt gt msgSend LCUENV tacServer MODBLCK TTPO Convert TY mrad2V 0 0 offsetY Measure the orientation of the TTP physical axes with respect to the horizontal
30. r mRad utin GE END ATTRIBUTE Vector signal tacMAX DATA NUMBER double BEGIN Value 0 0 0 0 0 0 0 0 0 0 END END endif END CLASS lsfDB DATA fntttpDB DATA BEGIN ATTRIBUTE fntttpDB DATA TTP TTPO ATTRIBUTE fntttpDB DATA TTP TTP1 FINITO Tip Tilt Platform Control VLT SPE ESO 15430 2786 E S O Software Detailed Design 2 31 08 2006 30 of 31 ATTRIBUTE fntttpDB DATA TTP TTP2 END END OF FILE 6 2 2 fntttpDB CONFIG class Ck ck ck KKK KKK AA A A AA Ck ck ck kk KKK KK KKK KKK ck kk ck KA KKK kk ck ko KA KK KKK KKK ck kk ck Ck ck KKK ko ck kk kk kk E 8 0 VLT project EC SId fntttpDB CONFIG class v 1 29 2006 06 28 17 21 01 vltsccm Exp Z who when what Jj Bszedeses Stee eier e EE e e Ee pduhoux 2000 04 06 created ZO include 1sfDB CONFIG class CLASS BASE CLASS fntttpDB CFG IFG BEGIN ATTRIBUTE double pixel2rad 0 ATTRIBUTE double saturation 0 ATTRIBUTE int32 enable 1 END CLASS BASE CLASS fntttpDB CFG BTK BEGIN ATTRIBUTE double gain 0 ATTRIBUTE double amplitude 0 ATTRIBUTE double threshold 0 ATTRIBUTE double timeout 0 END CLASS BASE CLASS fntttpDB CFG TTP BEGIN ATTRIBUTE fntttpDB CFG IFG ifg ATTRIBUTE fntttpDB CFG BTK btk END CLASS lsfDB CONFIG fntttpDB CONFIG BEGIN ATTRIBUTE fntttpDB CFG
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