Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 1 Design, Manufacture, Transport and Integration on-site in Chile of ALMA Antennas Agenda PM#4 PM# May 2006

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 2 PROGRESS MEETING #4 AGENDA May 17, 2006 – EIE / Venice (Italy): 10:00 – Welcome in EIE 10:15 – Engineering and design activities (Phase T2) Overview on-going activities 10:45 – Technical & Design Topics: Technical discussion and clarification about:  Antenna layout and azimuth platform  Metrology system: Summary and reporting of the activities performed during the mission at VLA site-  Quadripod legs and attachment 13:00 – Lunch

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 3 14:00 – Technical & Design Topics (Cont’d): Technical discussion and clarification about:  Cabin area on top of flange  Encoder status  Subreflector mechanism technical baseline 15:30 – Analysis and Error Budget: Description on-going activities 16:00 – System Engineering Activities status: Description on-going activities – VLA Site activities:  Drive system torque requirement:  Summary and reporting of the activities performed during the mission at VLA site  Derive actions for production Drawings delivered by AEM after completion of Phase T1  Review and comments from ESO

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 4 Design, Manufacture, Transport and Integration on-site in Chile of ALMA Antennas Antenna Layout and Azimuth Platform PM# May 2006

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 5 Update of the Azimuth Platform old new

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 6 Update of the Azimuth Platform old new

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Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 9 Design, Manufacture, Transport and Integration on-site in Chile of ALMA Antennas Quadripod Legs And Attachment PM# May 2006

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 10 Assembly procedure for Apex and Legs At the apex level the system has 3 degrees of freedom. (X,Y,Z)

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 11 Assembly procedure for Apex and Legs At the BUS level the system has 6 degrees of freedom.

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 12 First step: assembly of the leg and apex at the ground level. 1)Proparation of a jig with the following reference points:  Attachment of the legs with BUS.  Center of parabola. 2) Assembly of the 4 legs on the jig to the BUS interface reference points, with the auxiliary of the adjustable supports system. 3) Assembly of the apex on the legs. 4) Alignment of the apex working at the apex level system.(general assembly tolerance with respect to the nominal position: ±2 mm. on three axis x,y,z) 5) Fixation oof the apex.

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Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 14 Second Step: assembly on the parabola. 1) Disassembly of the adjustable supports 2) Assembly of the jig n°2 3) Disassembly of the legs and apex from the jig n°1 4) Assembly of the legs and apex on the BUS with the auxiliary of the spherical washers in order to compensate the errors at the level of the BUS interface.

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 15

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 16 Design, Manufacture, Transport and Integration on-site in Chile of ALMA Antennas Metrology activity on site PM# May 2006

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 17 METROLOGY ACTIVITIES AT ALMA TEST FACILITIES THERMAL METROLOGY - ACTUAL CONCEPT BASED ON 100 THERMAL SENSORS - CHECK OF THE CORRECT FUNCTIONNEMENT WIND METROLOGY - CHECK ABOUT A CONCEPTION OF WIND METROLOGY BASED ON A TILTMETER MOUNTED ON THE TOP ARM - CHECK OF THE BEHAVIOUR OF THE TILTMETER IN ALL THE OPERATING CONDITIONS

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 18 THERMAL METROLOGY APPARENT PROBLEM - THE CORRECTION DUE TO THERMAL METROLOGY GOES IN THE WRONG DIRECTION: THE POINTING ERROR IS INCREASED BY THE METROLOGY REAL PROBLEMS - IN THE ACU AN OLD CONCEPT OF THERMAL METROLOGY WAS IMPLEMENTED: WITH THIS OLD CONCEPT THE POSITION OF THE SENSORS PUTTED IN THE BASE STRUCTURE WAS CONSIDERED IN A WRONG WAY - THE ACU SOFTWARE WAS CORRECTED AND UPDATED - THE CORRISPONDENCE BETWEEN THE PHYSICAL SENSORS AND THE ROWS OF THE MATRIX WAS WRONG: SOME SENSORS IN THE RIGHT ARM WAS READ BY ACU AS THEY WERE IN THE LEFT ARM - ALL THE SENSORS WERE CHECKED AND NOW THEY ARE READ BY ACU IN THEIR CORRECT POSITION - THE POINTING MODEL GIVE A POINTING ERROR GREATER THAN THE ERROR DUE TO THERMAL DISTORSION

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 19 THERMAL METROLOGY APPARENT PROBLEM -THE CORRECTION DUE TO THERMAL METROLOGY SEEMS TO GO IN THE WRONG DIRECTION -BY POINTING POLARIS AND BY TRYING TO TRACK, AFTER A FEW TIME (i.e. 1 hour) YOU CAN SEE A POINTING ERROR AND IF WE TURN ON THERMAL METROLOGY, THE ERROR INCREASE -AFTER SOME EVALUATIONS AND SOME CHECKS, WE FOUND THAT THE CORRECTION OF THERMAL METROLOGY IS IN THE CORRECT DIRECTION -WE PUTTED THE ANTENNA WITH THE REAR FACING TO THE SUN, SO THE ANTENNA BEND ITSELF AND POINT LOWER. AFTER A FEW TIME WE TURNED ON THE METROLOGY AND THE ELEVATION CORRECTION WAS IN THE RIGHT DIRECTION REMAINING PROBLEM -THE POINTING MODEL GIVE A POINTING ERROR GREATER THAN THE ERROR DUE TO THERMAL DISTORSION

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 20 THERMAL METROLOGY REMAINING PROBLEM -THE POINTING MODEL GIVE A POINTING ERROR GREATER THAN THE ERROR DUE TO THERMAL DISTORSION POSITION AFTER 1 hour WITH A CORRECT POINTING MODEL POSITION AFTER 1 hour = ERROR DUE TO POINTING MODEL + ERROR DUE TO THERMAL STARTING POSITION POSITION AFTER 1 hour WITH METROLOGY TURNED ON POSITION AFTER 1 hour WITH A CORRECT POINTING MODEL AND METROLOGY TURNED ON = ERROR DUE TO THERMAL = ERROR DUE TO POINTING MODEL

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 21 THERMAL METROLOGY REMAINING PROBLEM WITH THE OPTICAL TELESCOPE IT IS VERY DIFFICULT TO ESTIMATE THE ENTITY OF THE POINTING ERROR MONITOR OF THE OPTICAL TELESCOPE 1 cm = ABOUT 30 arcsec POINTING ERROR TO CORRECT: 0.6 arcsec

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 22 THERMAL METROLOGY CHECK BETWEEN ROTATIONS PREDICTED BY THERMAL METROLOGY AND ROTATIONS OF THE TILTMETER POSITION ON THE TOP ARM

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 23 TM on Fast Motion mode 1. Reference a. Mission on Site April The settling time on the arms is about 20” -What we need to correct with the dynamic metrology? b. Technical Specification ALMA A-SPE Chap. 3.4 The Fast Motion mode are: - fast switching phase calibration - on-the-fly total power mapping -on-the-fly interferometric mosaicking

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 24 TM on Fast Motion mode a) fast switching phase calibration Assumptions: In the fast switching cycle, the antenna shall perform steps of 1.5 degrees on the sky and settle to within 3 arcsec peak pointing error, all in 1.5 seconds of time. The antenna shall then track and integrate on a calibration source during one second, then it shall switch back to the target source with the same requirements on switching time and settling accuracy. It shall then track on the target source. The time for a full cycle of target-calibrator-target observation shall be 10 seconds. General remarks: during the 10 seconds of cycle the thermal metrology system is not necessary due to the very short time, the metrology system shall be used only in the tracking mode What is the requirement in term of pointing error during the one second track? What are the environmental conditions during theoperational phases?

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 25 TM on Fast Motion mode b) on-the-fly total power mapping Assumptions: In on the fly total power mapping profile the antenna shall scan at a rate of 0.5 deg/s on the sky across a target source of one degree in size, then turn around at a distance of 1 arcmin, settle within 0.8 sec time scan back across the source in the opposite direction with a 2 arcsec RMS accuracy within primary operating conditions (as provided by the encoders reading, corrected with any metrology). This performance shall be attained up to 60 degrees elevation General remarks: In Primary operating condition the 2 arcsec of pointing requirement is meet only with the use of the thermal metrology system. No wind metrology system is needed.

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 26 TM on Fast Motion mode C) on-the-fly interferometric mosaicking Assumptions: In on-the-fly interferometric mosaicking, the antenna will scan at a rate of up to 0.05 deg/s on the sky across a target source, ranging from one arcmin to one degree in size then turn around and scan back across the source in the opposite direction. during the scans across the source the antenna shall follow the commanded path to within 1 arcsec RMS, within primary operating conditions (as provided by the encoders reading, corrected with any metrology). General remarks: What is the time for a full cycle? from the specifications it seems the the maximum scan across the source is 20”. If this is the time cycle in this short time we don’t need the thermal metrology system. In the prototype there was not requirement in terms of pointing errors. 3. Actions To have from ESO a clarification of the operational modes and pionting requirement during the Fast Motion mode.

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 27 PULL TEST OF THE RIGHT ARM LOAD APPLIED: N WITH STEPS EVERY 1000 N (LOAD AND UNLOAD) APPLICATION POINT: TOP ARM RIGHT (Z = 700mm BELOW ELEVATION AXIS) CONSTRAINT POINT TO GROUND: X = +20m FROM AZIMUTH AXIS Z = 500mm ABOVE GROUND LOAD APPLIED BY ONE TIRFOR (MANUAL) MEASURE WITH ONE DYNAMOMETER 1000 samples a 1/100s (decimation 9)

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 28 PULL TEST OF THE RIGHT ARM TILTMETER POSITIONED ON THE TOP ARM RIGHT

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 29 PULL TEST OF THE RIGHT ARM PULL IN DIRECTION +X ANSYS RESULTS: ROTY = 0.264E-04 rad = 5.45 arcsec MEASURED VALUES ON THE TILTMETERi ArmTiltX_arcsec_vs_kg = e-3 ArmTiltY_arcsec_vs_kg = e-3 YokeTiltX_arcsec_vs_kg = -6.96e-5 YokeTiltY_arcsec_vs_kg = e-3 Vectorial sum ArmTilt in direction Xyoketilt=-8.719e-4 Vectorial sum ArmTilt in direction Yyoketilt=-4.676e-3 REAL ANTENNA IS 16.6% MORE STIFF THAN ANSYS MODEL

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 30 PULL TEST OF THE RIGHT ARM PULL IN DIRECTION -Y ANSYS RESULTS: ROTY = E-04 rad = arcsec MEASURED VALUES ON THE TILTMETERi ArmTiltX_arcsec_vs_kg = e-3 ArmTiltY_arcsec_vs_kg = e-3 YokeTiltX_arcsec_vs_kg = e-3 YokeTiltY_arcsec_vs_kg = e-4 Vectorial sum ArmTilt in direction Xyoketilt=-2.513e-3 Vectorial sum ArmTilt in direction Yyoketilt=-5.199e-4 REAL ANTENNA IS 6.6% MORE STIFF THAN ANSYS MODEL

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 31 Fast Motion mode: Step response with maximal acceleration

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 32 Fast Motion mode: On the fly Mosaiking mode

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 33 Tracking mode: Maximal elevation tracking velocity.

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 34 Tracking mode: test on the repeatability position.

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 35 Conclusions 1.Thermal Metrology System General assumptions: -There was two errors in the previous thermal system:  Software code errors  Position of thermal sensors error -Resolution of the measurement system:  Pointing model not yet implemented in the antenna  Resolution of the screen Conclusion: -The direction of correction is ok -The system must be tested after the pointing model implementation in order to have evidence about the level of correction -For the Production we need to optimize the number and position of sensors in particular on the base structure

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 36 Conclusions 2. Wind Metrology System General assumptions: -The dynamic behaviour of the titlmeter in the top arm is not good -The dynamic behaviour of the titlmeter in the optical bench seems good -There is evidence of the hysteresys link to the azimuth bearing in both systems Conclusions: -We have to work in order to check only the error source that we need to correct (steady wind during the night, fast motion mode,…)steady wind during the night -The good position for the tilmeter is at the level of the optical bench -Different for the titlmeter system must be checked